A couple of years ago, I got some info about the amplifier setup at the sites from Terra - sharing here in case there is some useful info in there (our setup will be rather different, but it looked to me like our Amp is a 2017 vintage and it may be that the performance is not the same as reported in the 2019 paper).

collection of docs (table layout in 'Proposed....setup') : https://dcc.ligo.org/LIGO-T1700046

LVC 70W presentation: https://dcc.ligo.org/LIGO-G1800538 

I guess we should double check that the beam size everywhere (in vacuum and on the PSL table) is such that we don't exceed any damage thresholds for the mirrors used.