The show is huge, so it would be best to look online to help narrow your search. Then go to the show with your list and look for those models.
You won't find anyone looking under trailers and the sales force doesn't have a clue on how they are constructed. You have the right idea about looking from the ground up and understanding that you need a roadworthy vehicle first and the pretty stuff is secondary. One clue is to look at NCC (Net Carrying Capacity), the higher the better.
The only Northwood dealer in PA is
Arctic Fox, but they don't come to the show. If you can, take a look at their trailers first to get an idea how they are constructed.
