My wife and I are considering downsizing from a 40' 5th wheel to a camper van 21'-24' long. Looking at Roadtrek and Airstreams right now. Difficulty with 5th wheel range from 2 blown tires and $9,000...
If you already have a tow vehicle and want to keep it, a small trailer would be a far better deal. You can get decent tank capacity and reasonable storage in a 21-24 foot trailer.
Spend some time in a B TOGETHER before you buy. They are pretty cramped. It might be too much of a downsize to manage.