The stuff people actually use would be a good start.
Chocks and levels, spirit levels, power cords and amphibians, gas bottle stuff, peg removers, heavy duty pegs, those surprisingly useful little knobs that go on top of poles to keep them in place, extra poles, annex matting, those little folding stools/steps, BEST water filters, and some water connections bits and pieces, hose bags, plastic drawers/boxes that fit perfectly in your brand of camper, cgear matting or tarps for under the camper.
Leave the chairs and tables to Rays etc as they take up too much space in the showroom and too many $ invested. Tell people who has the best prices locally, and you'll appear more honest.