Every time I go to bed in my trailer my furnace is left unattended. If it could not run unattended it would be worthless. Do understand though that if you do not have electricity where the trailer is, it will run only as long as the battery lasts. For a single 12 volt this is often less than one night. If you do have electricity it will run unattended until it runs out of lp gas. Might be a better option in that case to put a small electric heater inside. Just be certain it is well away from any combustable materials. We run ours sitting on the open oven door.
Good luck / skip