I would suggest that you make plans to visit the HUGE RV show that is held every January at the Florida State Fairgrounds near Tampa. Figure on spending at least 2 days. Everything will be there, including RV accessories. You will be able to walk thru every type of 'camper' and 'RV' that is available. This may be the biggest show in the country.
I note you want to buy used. I still recommend you go to this show as you will be able to see all the different types and sizes available, and also floor plans. It is a GREAT planning tool.
Tim