I once traded in a car with hail damage. Insurance would either total it, or give me a slightly less amount and I would keep it and it would NOT be considered totaled. I chose the lesser amount and kept it. Insurance company would have given me less on future repairs with this option, so we decided to trade it. I got an excellent trade value from the dealer as it was. (not sure how I pulled that off) I also got the check from the insurance company for the repairs. I used the trade in value from the dealer AND put the money from the insurance company as a further down payment.
I assume that the camper will work the same way in a sense. Not trying to speculate though. It all depends on what "he said she said."
With that being said, it is probable that the dealer has no interest in the damaged camper. Chances are that the dealer was able to knock off 2500 anyways. He used the trade as a way of making you think they were helping you out of a jam so you were more inclined to buy. Dealers like to play mind games. Either way, if you are happy with the terms, then don't worry about it and enjoy your new rig.