I am also not a fan of vaccinations...but am currently taking everyone here in for their booster :-( for rabies.
Sadly, even totally indoor animals should have current rabies shots. A few years ago in Saskatoon, a cat that had NEVER been outdoors...in fact lived in an apartment so the chance of getting out at all was slim...contracted rabies. Nobody could figure out how..until one of the people remembered there had been a bat in the building a couple weeks before.
Also, if you are doing this type of rescue and taking in strays...you could consider being vaccinated YOURSELF for rabies. It's not a painful shot (first time I had it was a series of two about 3 weeks apart if I remember right) and I did not need a booster for YEARS. The cost of the booster was about 130.00..but was well worth the money when I was working in a vet clinic.