Use the metal snap locks to keep your horse from getting loose. There is a short rope sold that is called a trailer tie. It has metal fasteners on both ends and is used inside the trailer while transporting your horse. Also works outside the trailer too.
Sometimes, used horse transporters are available on ebay. Not seen any lately but that is because I have not looked. Most were used to transport race horses so the inside height should not be a problem. Some had diesel engines and others gasoline engines. One thing to be aware of is if the truck has hydraulic brakes and has been sitting a year or two. You may be in for a case of sticker shock when you see the costs of a brake rebuild job. In a few weeks I will have the brakes repaired on an old fire truck that has been sitting for three years. You will get an idea of what to expect should you decide to get one. Air brakes are much better and do not give the trouble that hydraulics do but then you run into the special driving license part called CDL. Unless it is for farm or RV use, in my state anyway, not sure about the rules in your state. Hope this helps. : )
Engines? Brakes? HMM I was thinking more on the lines of panel, carpet, microwave ....:') Thanks for the info.
My battery is dead this morning:'(. This isn't a priority or anything but I was just wondering why they don't sell combinations. Seems like there would be a market. Maybe cost would be too high or something. I was surprised about the living quarters ones though. They weren't any higher than some new travel trailers.