1. Make sure the floor plan will work-- keeping mind you mentioned your taking month long trips. Make sure there is sufficient storage.
2. Fleck for any signs of leaks-- check ceiling and corners/ don't forget in the cabinets. Check under windows-- check caulking- ask how often the caulked all joints (should be done annually). Double check for any leaks in overhead area. Start all alliances. Open the fridge vent check for any yellow dust (that would indicate a leak in the fridge-- that is a huge expense (>1K).
3. How old are the tires--- had been used regularly-- engines that sit not being used are worse than engines driven in fairly regular basis.
Good luck. --- the pricing seems readonable if in good condition