Many people seem to be making their RV trailers into small homes and calling themselves full timers. Some are purchasing them new, never to be used on the road.
In our travels we have taken notice of residential sections of large RV parks. And, sure enough a high percentage of them are TTs and 5th wheels. However, up in the northern states the RV park models are popular. I don’t know why but maybe it’s because they are easier to insulate.
Anyway, here is a picture I took while traveling in NH.
It’s my guess that because they are basically an RV and sold as an RV they would be registered as an RV.