Many of the smaller camper and PUPs require under seat storage. It is the trade off for a smaller size.
The problem with the dealers is they have no idea of how you camp. Your van has a specific tow rating that anyone can look up. It also has a cargo rating that is vehicle specific.
The dealer sees your van can pull 3000# and the TT weighs 3000# you are good to go in his book. He had no idea weather your family travels light or packs 1000# of toys and gear into the TT.
This is the situation almost all first time buyers face. Mostly because they have never heard of tongue weight, gross trailer weight, vehicle max cargo capacity. Add to this the literature only speaks of dry weights and it can be quite misleading.
Good luck
