I don’t think those dings would stop me from buying the trailer, but I would want a few bucks off. I’d be honest about why you didn’t replace the panels and punt them out. If I was buying a trailer with obvious dings on it (even though they’re cosmetic) and the seller said they never noticed them, especially on a maticulously maintained trailer, I would walk because I’d assume they’re lying.
When we upgraded, we traded in the old trailer. Ours was also maticulously maintained and I could get top dollar for what it was. The dealer offered a very fair price. The upside was we were never without a trailer. The new tt was ordered (not by us, pre-ordered by the dealer) and we had to wait a couple of months for it. We didn’t want to sell ours and be without a tt, and we certainly didn’t want to have two trailers!
Have fun shopping.