Welcome!
Your 200# tongue
weight rating is going to be the limiting factor. You need a trailer with a fully loaded
weight under 2000# to maintain at least 10% tongue weight for stable, sway-free towing. That limits you to a 13’er with a single LP tank on the tongue.
Scamp makes more 13’ers than anybody else, and that’s where I’d start looking. There’s a front wet bath model as well as a front sofa/bunk layout with a storage compartment for a porta-potty and the option of an outdoor shower. Both have a small but complete galley. There are deluxe versions with custom wood cabinetry if you prefer. A larger rear dinette bed (54”W vs. standard 44”W) is available, but it steals space from the galley and storage closet.
Happier Camper (Los Angeles) and
Armadillo (British Columbia) also make 13’ models with bathrooms in some layouts. They’re both a step above
Scamp in price and build quality.
13’ers are quite small- the cabin is only 10’ long and 6.5’ wide- so you’ll want to get a first-hand look before deciding if this will work for you. I was surprised at how roomy the front bunk layout feels and how efficiently the space is used. However, beds are small and storage is limited. We used ours with four people for over ten years, but we took shorter trips of up to a week at a time. We recently became empty nesters.
We tow our 13’
Scamp with a Pilot, and it does well in the mountains where we live. Since you will also presumably do a fair amount of mountain towing, I definitely wouldn’t go any larger. The H6 in your Subaru has the power, but the transmission is the weak link. Check the towing section of your owner’s manual for details and caveats. In many years of towing, my advice is not to push the limits of your vehicle. Choose a trailer that’s comfortably within your vehicle’s ratings, and don’t forget to factor in what you will carry in the vehicle besides the driver.