Welcome to the best l'il trailer forum in the world wide web!!
Speaking of little, you said 17-20', but several of your choices are shorter than that, so I thought it'd be worth pointing out the difference between overall length (tongue to bumper) and cabin length (living space). The difference is usually around 3' unless the unit has an extended tongue or bumper for storage.
Conventional framed trailers designate their models by cabin length, which means the overall length will be about 3' longer. Say you're looking at a Jayco 17RB (don't if that's a thing or not, I just made it up). It has a 17' cabin, so the total length will be around 20'.
Molded fiberglass trailer manufacturers (and Airstream, BTW) designate models by overall length, so the cabin is around 3' shorter
. That's actually the older convention, so it's not marketing exaggeration or fish stories. A Casita
17SD (that's a real thing!) has a cabin that's about 14' long.
Since many molded trailers are narrower too, the living space is quite compact. Baths are wet baths: toilet and shower in one waterproof enclosure. Beds are narrower and shorter than your bed at home (the main bed in most Scamp
16's, for example, is only 45"x76"). Many have interior heights not much over 6' and a few are less.
I'm not trying to discourage you; we love our small trailers (and there are a few larger molded fiberglass trailers). Just things to be aware of as you do your research. These are virtual times, but it's hard to get a feel for the actual space from a photo or floorplan. In the end there's no substitute for a first-hand look.
Best wishes in your search!