I too would be inclined to go with a small cube, or a wall mount like Jim's. We keep a small cube in our trailer, but it has been a couple years since it was used. It seems the only time we camp with 120V hookups, it is way too hot to need heat anyway.
2017 Escape 5.0 TA (someday soon, I hope
2015 Ford F150 Lariat 3.5L EcoBoost
2009 Escape 19 (previous)
“Most folks are about as happy as they make up their minds to be.” — Abraham Lincoln