bertb- Yes one could have salvage RP (surgery), after radiation....it is rarely chosen or mentioned, but can and has been done. It would make surgery more difficult, just like doing HT drugs prior to surgery can make it more difficult, but still can be done.
Some things to consider on radiations: dosemetrics (dose amounts can vary, but total overall exposure does have a limit that the system seems to endorse as a maximum amount, not everyone gets the max amount), types of delivery vary, penetration or depths of ray depositing (IMRT much safer than old box radiation or ebrt), also types of rays used might in fact make a difference because they can interact with the cells in different ways, especially neutron rays (very rare but most powerful and works differently than photon or proton). You can read some of this info in Dr. Strum's book A Primer on Prostate Cancer (2nd edition). Currently only one neutron machine running in the USA, so now super rare to get, requires a huge Cyclotron machine and knowledgable radiologist in using this type of technology. Back in 2002 you could get neutron ray machine used along with IMRT photon machine in a sequence combo thing (Karmanos Cancer Center/DMC Detroit), I know because it is what I chose as my main treatment, after getting 8 opinions and a denied surgery by Dr. Menon (who righteously assessed my high risk stats and variables). So far 10 yr.+ mark now, that is the good news.
Good luck on your choice and going forward in this, you might wish to read about Bolla Abstracts on HT and radiations, it shows longer survival or better results for PCa patients.