Dave, First mods are adding a
fridge, tongue box, and shelves in the closet and by our feet over the bed. After that I have to keep my daughter from rolling out of bed, replace the carpeting with laminate (allure), and weld a receiver on the back to haul bikes.
Brakes are weak as well. As to where to look, I used this site and craig's list. Type "search all of craig's list" into your search engine and you will get a list of places that do it. Try a few because they have different useful features such as how far you are willing to drive, etc.... I looked at other sites, but didn't find them as useful. Other members may have good suggestions for where to look as well.