Depends on state law. In California, a mobilehome cannot go on an RV space, but an RV can go on a mobilehome space.
But PARK MODEL RVs can go on RV spaces, and in California, those are defined as 400 square feet or less, licensed by the DMV. There are really well built park models that are better construction than many older stick-built single family homes. So those are a great alternative for RV spaces.