Where in the New England area, State closest city is fine. I'm in NY myself near Cooperstown.
Rust on a Camaro can be VERY nasty due to the lack of a real frame. The bodies structure is made up of layers of formed steel welded together to form the various parts. Then a front subframe is bolted to this and that carries the engine and transmission. In the rear there are formed sheet metal sections that hold the rear suspension to the vehicle. Rust in those areas is a very bad thing and can be very hard to kill.
I have scrapped out cars that looked just fine from the outside but the uni-body was rotted so bad that it would cost more than the car would ever be worth to fix.
You say mice got into it. That is a bad thing, they like to chew into wiring, seats, carpet padding, they will even crawl into the intake if they get the chance. Nasty little critters.