That may depend on the quality and type of upholstery material and vary from manufacturer to manufacturer. I'd check the camper's manuals and if there isn't an answer there try to get one from the manufacturer or a dealer.

We have a non-steam upholstery cleaner that we used for spot cleaning on the Flagstaff, when we had it. I know there is a huge difference between the upholstery material and the overall fit and finish on the Niagara we now own compared to the Flagstaff. Just based on that, I'd be hesitant to make or get a recommendation unless it was tried and known to work on the same make/model.

John