I have traded in two and on both the dealer quoted the trade sight unseen. Both honored that quote when delivered. They know what they're doing and any way you look at it are giving you nothing more than wholesale so you're taking the typical soaking, but it can be convenient and sometimes makes the most sense. A lot of trades head straight to the auction, especially in MI where they seem to have a lot of dealer auctions with RV's for some reason.
I've negotiated a couple times at a distance with Lakeshore, I believe her name was Cheryl. From what I experienced they will give you straight up numbers new and trade. Low and agreeable/reasonable price on new and wholesale trade, but will flat out tell you they are not really interested in trades.
You may want to check into
THESE GUYS. They're really good as far as dealers go, and may have something that interests you or can get you what you want at the right price. They certainly won't screw you on a trade. And it may save you a little traveling as far.