I’ll say if you can caulk or seal up any issues with that and don’t care about the aesthetics of it then go for it.
Not a lot of important structure up there, and it doesn’t look “that” bad.
Considering new ones go for $13-16k usd, one that’s not damaged and 4 years old is worth around $10k tops.
To fix that right, the whole side panel needs replaced plus whatever repairs under the skin which is a significant % of the retail value of a camper that inexpensive.
Bottom line, the dealer doesn’t want to repair it because they’ll likely have more into it than it’s worth. And they didn’t give much on trade.
It either should be a great deal like $5k usd or walk away.
Rough numbers, figure the actual value yourself and of course check out the rest of the camper works and in good shape