Casita 17' models are somewhat heavy, especially on the tongue (averaging about 3200 pounds with 415 pounds tongue weight). If your tug can accommodate that, or if you're planning to upgrade, fine. If not, the Liberty is also available in the 16' length. Know that the Independence and Liberty do not have a separate dinette area.
Side dinette models from
Casita and
Scamp can be used as two separate beds- one person takes the big dinette and the other takes the small dinette. Ditto the
Scamp 16' side bath model. The bath is small but complete, it has a second bed across the front, and way more galley space than any of the others.
If you really like the smooth
fiberglass interior of your Burro, and you can live with an all-electric set-up, you might want to check out the
EggCamper, also a double hull design. It can also be set up with one bed across the back and one along the side. Some early builds did include
propane. Very spacious and fairly
light for their size. I don't think any are being made right now, but used units appear from time to time.
Lots of ways to get what you want if you look beyond traditional side-by-side twins. You could even modify the big dinette to make a U-shaped bench with a single bed across the back (with the sides still available for dining) and use the side dinette or front sofa for the second bed. In 17' or less, that's actually the best way to get two beds and a place to eat, along with a galley and wet bath, all at the same time.