Check EVERYTHING for faults while the camper is still at the dealership. Put some water in the fresh tank and test the water system pump and lines. Slide outs are commonly troublesome. So are batteries,generators, refrigerators, AC, & water and drain line connections. Do the stove burners and oven light easily and does the microwave work? Large campers have electric brakes. Is a controller for your tow vehicle built in or included in the purchase? Do the camper's brakes actually work? Open a cupboard and watch the water pump for leaks, Inspect the sewer drain hose and connections. Is there a built-in spray for rinsing the black water tank? Go up on the roof and carefully inspect the caulking. If it's not somewhat pliable, it will soon crack and leak. How are the tires? If a 5th wheel, will it be level when being towed? If it's a flat trailer, is there an equalizing hitch? Is there ANY evidence of rodent intrusion? If they got in once, they will again.
We have a camper that fits in the pickup box because we travel with it. But they have the same problems any RV has. 20+ years of camper ownership has taught us a few lessons the hard way (trial and error).
Read owner's forums at RV.net, NATCOA.com (a truck camper website), Lance Owner's of America, etc. Potential problems will be addressed in owner's forums.
I'd look for a camper with a cold weather package. The thermopane windows and extra wall insulation helps for heat as much as for cold. The industry standard for "Four Season" certification is meaningful, but so called "cold" or "arctic" packages are maker's trademarks, not industry standards.
If you won't be using the RV for a few days, drain everything. Once the chlorine has evaporated from water, sulfur bacteria will make any water left in the system (lines, tanks, and water heater) smell bad. Never leave anything in the grey or black water tanks while it RV is sitting idle.
