I would think a B, some type of van conversion, if it is always just you, and if you are always moving. It is a RV size that can work for one person with a lightweight lifestyle, and a vehicle size that can go and park almost anywhere, including most places in most cities.
Few of the "factory" B's are designed for a single person's longer term living needs, but Sportmobile does custom layouts and builds, if you can figure out what you would like to have inside.
If you will be going someplace to stay a long time, then you do need something else for getting around. If your home is a motorhome, that means towing another car (where I am now). Recently widowed, and accustomed to extended trips with extended family, this 30 foot of motorhome is really too much house for me, and my daughter has her eyes on it, but for now, it is workable.
If your home is towable, it can be left in place and your tow vehicle is your "get around" vehicle. For a single person's space needs, this could be a small travel trailer and a small van or truck (if the trailer is small enough, a minivan). I have a friend, another widower, who has been traveling and touring this way for several years, 17-foot Casita behind a Chrysler minivan. It works for him alone, or with one companion. RVSue (you have a link) is pulling her Casita with a full size van, and has made it more of a utility vehicle supporting her travel trailer.
A van or minivan as a tow vehicle can be outfitted for part-time living, bed and cooking gear, maybe a portapottie a home away from home for extended outings away from the trailer and campsite. A lot harder to do that if your house is a motorhome and towed vehicle is a small car. I think I'm headed this direction, when I am through making extended family road trips.
People are going to say "I can't live full time in that small a space," if you talk about a B or a small trailer. Maybe they can't, maybe you can, it is up to you to figure out. Some people need a 2400 foot home all for themselves or as a couple, others live with a family of three to six in a 400-600 sq ft three room flat or house trailer. It's a matter of adjusting lifestyle.
Just my thoughts. Not all that different, single guy or single gal, depending on what you are doing.
So to start, think about your travel pattern. Would you be moving every day, or would you be parking for a while and wanting to get around? Do you want to be in cities, RV resorts, campgrounds, or living out in the boonies like Sue.
