Many large RV dealers will order furniture you, but few stock it or offer a showroom. I've seen small displays in a few very large Camping World outlets.
Replacement furniture for RVs is a very small market. I don't think you are going to find much to browse unless you find a trade show somewhere for RV manufacturers or conversion van upfitters, If anyone is operating a major showroom it would be where RVs are manufactured, northern Indiana and southwestern Michigan, and those would be surplus stores in most cases.
I saw a suggestion for Colaw's, but the last couple of times I visited that one, they did not have a showroom for new furniture, just some takeout pieces or surplus items in the racks.