Been a lot of developments in gas fireplaces, propane or natural gas. From 'zero' clearance installation near combustible surfaces to the 'ventless' fireplaces. That said, a gas burning fireplace in an RV without venting to the outside would not make feel warm and fuzzy on a cold winter night. My brother had a ventless natural gas model in his prior stick n'brick. Don't care how safe it was claimed to be, I asked him to open a window while we visited and it was in operation. Damn thing gave me a headache which had to be all that CO that wasn't supposed be venting to the room.