Having raised raccoons (I'm a wildlife rehabilitator), they will climb the fence or most likely go up the trees and into the cage that way.
You'll have to find a way to secure the top somehow, or make sure they are secure at night at the least.
I'm pretty sure, even a raccoon could cause enough problems and get a garbage can open too and get them out. They are very smart!
Good luck! You sound dedicated and loving it!