Honestly, if you are going to full time you will need a trailer with at least 1 slideout. You do not say how old your son is, but all kids need some room to stretch out. If I were to do what you are planning on doing, I really would look at a 5th wheel. Most of them are built better (not all) and have more room. Very stable on the road. And you said "be able to be self sufficient if we camp at an event that does not have hook ups." Most 5th wheels also have larger water and waste tanks, room for larger propane tanks and batteries.
Something like this: http://www.northwoodmfg.com/images/rsync/floorplans/mountain-335BHS.gif
