Sorry about the recurrent PCa. You are certainly going to the right place.
Just a comment about Mayo/Rochester in January/February. My PBT treatment was in late Jan/early Feb 2020. Despite the fact that I live in a winter climate I too thought Rochester wouldn't be fun and considered going to Mayo/Scottsdale AZ. Glad that didn't pan out for other reasons.
I used the tunnels between bldgs (sometimes called the subway), but I also found walking out-of-doors more expeditious. (The tunnels can be a maze.) If you are going to be there a while there is lots to experience: Public library cards for visitors for $1/wk, there is a great food coop (can eat there), probably some public music & theatre events have restarted. I took an Uber to/from a great traditional barbecue restaurant (the Uber cost more than the meal). Take an organized tour of the art work at Mayo. Go visit the (Mayo) Plummer bldg (a gorgeous art deco palace) - I think there is a Mayo history museum in the Plummer.
Dining opportunities are diverse but some may still be closed.