In general, yes, you can use a regular-sized mattress in your RV. However, depending on the size of the mattress, you might need to adjust how you set it up inside the vehicle. For example, if you're looking at a full-size mattress, you'll probably want to put it down on the floor. But if you're looking at something like a twin mattress, you'll want to consider putting it on a bunk bed frame. However, short queen mattresses are built for tight spaces making them excellent options for RVs.