Having owned two Casitas over twelves years and camped and pulled them thousands of miles, my wife and I found the Casita's Dexter torsion single axle, along with a low center of gravity, really hugged the road. There was never any sway and they towed like a dream. And my wife and I towed them with two different Ford Explorers and our current F-250 diesel truck.
FYI, for those who do not know, fiberglass Casitas are completely enclosed under the bottom, unlike some conventional square frontal wood or aluminium framed, rectangular shaped, trailers. This contributes to less air drag underneath. Casitas are essentially two egg shaped, fiberglass clam shells fused together; a top and bottom half. Other fiberglass trailers are designed and built in a similar manner.
When it comes to overall towing ease, suspension flex, braking characteristics, and other factors, I would think you would consider comparing apples to apples; pull and compare a single axle Casita with a similar single axle box shaped trailer.
Yes, if more interior space is important by all means chose the box trailer. Space did eventually did become more important to us as more grandchildren came along and we now own another traditional box shaped trailer with an aluminium frame.
But if towing characteristics is important, for a couple of adults and child or pet, I do not believe Casitas, single axle small Airstreams or similarly designed and shaped trailers can be beat.
Perhaps there is an engineer who is familiar with air flow or towing design characteristics can chime in to help with your choice.
Finally, somewhere in this forum is a link survey of owners of all different types of travel trailers which may be useful to you when making your decision. Perhaps someone will post the link.
Sorry for the long post. Good luck with your choice and happy camping!
