As long as you check it out thoroughly - all the wires and hoses, it should be o.k. Yes, rodents in RVs are common, depending where it's parked. That's no big deal.
What size is your Class C with three slides and the Class A? To me it doesn't seem like you're gaining a lot of space especially if you're not going to be traveling but rather sitting for a long period in campgrounds.
Your Class C was bought new and it's a newer unit. There must be something other than room that you're willing to give it up.
Only you can judge if it's a good deal for you.
