Towing with a Wrangler means it'll have to be a small, light trailer (check the Jeep's towing capacity). And you'll likely need a weight distributing hitch (WDH). And you'll definitely need a brake controller for the trailer brakes.
If he's going to be in an RV park, then he'll want full hookups so he can dump the waste tanks without having to hookup the trailer and travel. If not in an RV park, then he'll need to figure the logistics of dumping every so often (depends on tank size and frequency of use). Kitchen tools, plates and utensils, bed clothes, broom/mop/vacuum, towels, kleenex, etc.
Check out the library (link just above the ads) for lots of checklists, maintenance items, things for newcomers to know, driving tips and more.