here is a Matlab code to try to optimize the telescope for a hot cavity,
taking into account the thermal lens in the coupling mirror.

from that code, one can deduce using the "Gaussian Beam" software (using the attached xml file) an optimized telescope with 100% geometrical coupling @ Pcav = 700kW and absorption in the coatings = 0.6ppm

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE gaussianBeam>
<gaussianBeam version="1.1">
    <bench id="0">
        <wavelength>1.03e-06</wavelength>
        <leftBoundary>0</leftBoundary>
        <rightBoundary>3</rightBoundary>
        <targetBeam id="0">
            <position>1.884</position>
            <waist>0.0005927</waist>
            <positionTolerance>0.1</positionTolerance>
            <waistTolerance>0.01</waistTolerance>
            <minOverlap>0.98</minOverlap>
            <overlapCriterion>0</overlapCriterion>
        </targetBeam>
        <beamFit id="0">
            <name>Fit0</name>
            <dataType>1</dataType>
            <color>4278190335</color>
            <data id="0">
                <position>0</position>
                <value>0</value>
            </data>
            <data id="1">
                <position>0</position>
                <value>0</value>
            </data>
            <data id="2">
                <position>0</position>
                <value>0</value>
            </data>
        </beamFit>
        <opticsList>
            <inputBeam id="2">
                <waist>0.0001447</waist>
                <index>1</index>
                <M2>1</M2>
                <position>0.189</position>
                <name>w0</name>
                <absoluteLock>1</absoluteLock>
            </inputBeam>
            <lens id="5">
                <focal>0.25</focal>
                <position>1</position>
                <name>L3</name>
                <absoluteLock>0</absoluteLock>
            </lens>
            <lens id="6">
                <focal>-0.15</focal>
                <position>1.25</position>
                <name>L4</name>
                <absoluteLock>0</absoluteLock>
            </lens>
            <lens id="11">
                <focal>0.457</focal>
                <position>1.979</position>
                <name>L4</name>
                <absoluteLock>1</absoluteLock>
            </lens>
            <dielectricSlab id="8">
                <indexRatio>1</indexRatio>
                <width>0.01</width>
                <position>1.979</position>
                <name>D2</name>
                <absoluteLock>1</absoluteLock>
            </dielectricSlab>
            <dielectricSlab id="7">
                <indexRatio>1</indexRatio>
                <width>0.01</width>
                <position>2.6708</position>
                <name>D1</name>
                <absoluteLock>1</absoluteLock>
            </dielectricSlab>
        </opticsList>
    </bench>
    <view id="0" bench="0">
        <horizontalRange>3</horizontalRange>
        <verticalRange>0.009999</verticalRange>
        <origin>0</origin>
        <showTargetBeam id="0">1</showTargetBeam>
    </view>
</gaussianBeam>

clear
clc

c=3e8;
lambda=1030e-9;
Pin=35;
Gcav=20e3;

%% 2M-cavity geometrical setup definition
FSR=216.67e6;           % Free Spectral Range of the FP-cavity
Lrt=c/FSR;              % round trip distance in the FP-cavity
L=Lrt/2;                % distance between mirrors
iR10=0;                 % cold ROC of M1
iR20=1/2.241;           % cold ROC of M2

%% 2M-cavity thermal setup definition
A_Coating=0.6e-6;       % absorption in the coatings
% Heraeus Suprasil 3001 parameters
n_Sup3001=1.45;         % refractive index for Fused Silica
A_Sup3001=0.3e-6;       % 0.3+/-0.2 ppm/cm @ 1064nm
kappa_Sup3001=1.38;     % 1.38 W/m/K @ 20°C    / 1.46W/m/K @ 100°C
alpha_Sup3001=0.6e-6;   % 0.51ppm/K @ 0-100°C / 0.59ppm/K @ 0-300°C
beta_Sup3001=8e-6;      % cf Suprasil 3001 documentation
% Corning 7972 ULE parameters
n_ULE=1.45;             % refractive index for ULE
kappa_ULE=1.31;         % 1.31 W/m/K @ 25°C
alpha_ULE=10e-9;        % Premium grade < 10ppb/K
beta_ULE=11e-6;         % 11.24ppm/K @ 40-60°C / 10.68ppm/K @ 20-40°C

%% 2M-cavity cold mode definition
zw0=iR10*L*(1-iR20*L)/(iR10+iR20-2*L*iR10*iR20);
zr0=sqrt(L*(1-L*iR10)*(1-L*iR20)*(iR10+iR20-L*iR10*iR20))/(iR10+iR20-2*L*iR10*iR20);

% complex radius at z=0 (M1)
q0=-zw0+1i*zr0;
% beam size at z=0 (M1)
wm10=sqrt(lambda/pi/zr0)*abs(q0);
% complex radius at z=L (M2)
qL=L-zw0+1i*zr0;
% beam size at z=L (M2)
wm20=sqrt(lambda/pi/zr0)*abs(qL);

% beam profiler position
Lb=0.67;
% definition of the z-axis
Nz=1e3;
z=linspace(-zr0,L+Lb,Nz);
idm=z<=0;
idp=z>=0 & z<=L;
idb=z>=L;

%% telescope definition
% cold optimization
zwT=zw0;
zrT=zr0;
% hot optimization
zwT=-0.38;
zrT=0.155;
qT=z-zwT+1i*zrT;
wT=sqrt(lambda/pi/zrT)*abs(qT);

%% geometrical coupling definition
C0=4*zrT*zr0/((zwT-zw0)^2+(zrT+zr0)^2);

Nk=200;
Pcav=zeros(1,Nk);
C=C0*ones(1,Nk);
wm1=wm10*ones(1,Nk);
wm2=wm20*ones(1,Nk);
kt=0.05;
iR1th_f=0;
iR2th_f=0;
iR1thl_f=0;
iR2thl_f=0;

figure(1)
clf
hold on
grid on
xlabel('z position (m)')
ylabel('beam size (µm)')
plot(z(idm),wT(idm)*1e6,'r')
ylim([0 900])

for k=1:Nk

    % cavity power
    Pcav(k)=Gcav*C(k)*Pin*(k>1);
    % absorbed power in coatings
    Pa=A_Coating*Pcav(k);
    % thermal ROC for M1 and M2
    iR1th_i=-alpha_Sup3001/(2*pi*kappa_Sup3001*wm1(k)^2)*Pa;
    iR2th_i=-alpha_ULE/(2*pi*kappa_ULE*wm2(k)^2)*Pa;
    % thermal lens for M1 and M2
    iR1thl_i=beta_Sup3001/(2*pi*kappa_Sup3001*wm1(k)^2)*Pa;
    iR2thl_i=-0*beta_ULE/(2*pi*kappa_ULE*wm2(k)^2)*Pa;

    % slow thermal effect simulation
    iR1th_f=iR1th_f+kt*(iR1th_i-iR1th_f);
    iR2th_f=iR2th_f+kt*(iR2th_i-iR2th_f);
    iR1thl_f=iR1thl_f+kt*(iR1thl_i-iR1thl_f);
    iR2thl_f=iR2thl_f+kt*(iR2thl_i-iR2thl_f);

    % total ROC for M1 and M2
    iR1=iR10+iR1th_f;
    iR2=iR20+iR2th_f;
    % total ROC in tranmission for M1 and M2
    iR1t=iR10+iR1thl_f;
    iR2t=iR20+iR2thl_f;

    % cavity mode parameters
    zw=iR1*L*(1-iR2*L)/(iR1+iR2-2*L*iR1*iR2);
    zr=sqrt(L*(1-L*iR1)*(1-L*iR2)*(iR1+iR2-L*iR1*iR2))/(iR1+iR2-2*L*iR1*iR2);
    q0=-zw+1i*zr;
    qL=L-zw+1i*zr;
    q=z-zw+1i*zr;
    w=sqrt(lambda/pi/zr)*abs(q);

    % beam from telescope to cavity
    zwTA=(zwT+2*iR1t*(zrT^2+zwT^2))/(1+4*iR1t*zwT+4*iR1t^2*(zwT^2+zrT^2));
    zrTA=zrT/(1+4*iR1t*zwT+4*iR1t^2*(zwT^2+zrT^2));
    qTA=z-zwTA+1i*zrTA;
    wTA=sqrt(lambda/pi/zrTA)*abs(qTA);

    % beam after the cavity
    zwOUT=(zw+2*iR2t*(zr^2+zw^2))/(1+4*iR2t*zw+4*iR2t^2*(zw^2+zr^2));
    zrOUT=zr/(1+4*iR2t*zw+4*iR2t^2*(zw^2+zr^2));
    qOUT=z-zwOUT+1i*zrOUT;
    wOUT=sqrt(lambda/pi/zrOUT)*abs(qOUT);

    % plots
    plot(z(idp),w(idp)*1e6,'k')
    plot(z(idp),wTA(idp)*1e6,'r')
    %plot(z(idb),wOUT(idb)*1e6,'b')

    % coupling calculation
    if k<Nk
        wm1(k+1)=sqrt(lambda/pi/zr)*abs(q0);
        wm2(k+1)=sqrt(lambda/pi/zr)*abs(qL);
        C(k+1)=4*zrTA*zr/((zwTA-zw)^2+(zrTA+zr)^2);
    end

end

figure(2)
clf
plot(Pcav/1e3)
grid on
ylim([0 max(Pcav/1e3)])
ylabel('cavity power (kW)')

figure(3)
clf
plot(C)
grid on
ylim([0 1])
ylabel('coupling (A.U)')

zwT=(zw-2*iR1t*(zr^2+zw^2))/(1-4*iR1t*zw+4*iR1t^2*(zw^2+zr^2));
zrT=zr/(1-4*iR1t*zw+4*iR1t^2*(zw^2+zr^2));

disp(['waist position for telescope from hot cavity  : ' num2str(zwT) ' m'])
disp(['Rayleigh length for telescope from hot cavity : ' num2str(zrT) ' m'])