There is no easy answer for that. Everyone travels differently in an rv and values different things so it is a personal choice on rv and floorplan. With a 24ft trailer you may have trouble finding a class c that will handle that. It depends on the weight. Maybe you could find a superc that might handle it but they arent cheap.
A typical 24-foot racing trailer, depending on the construction materials and features, would generally weigh between 3,000 and 4,000 pounds when empty, with a Gross Vehicle Weight Rating (GVWR) usually ranging from 9,000 to 10,000 pounds, allowing for a significant payload capacity to carry a race car and equipment. There are very few class C units that would safely tow that loaded trailer. Most are built with a hitch receiver that is rated for no more than 5000#. You need to be looking at the super C models if you intend to tow the trailer fully loaded and with a car inside.
The enclosed trailer is alum framed and skinned. It weighs about 3000 lbs and I have a 1450 lb car in it. I think I have another 1000 lbs of stuff in it. The Thor 28VT has a 8000 lb hitch. We would use it for 5 or 6 races per year and possibly more when I retire
The Gross Combined Weight of the Thor model we are looking at is 22,000 lbs. Gross Vehicle Weight is 14,500 lbs. So the race trailer loaded is around 5500 lbs.
You might keep in mind that, in addition to the weights involved, your towing rig will need to be able to handle a LOT of wind load while traveling. RVs typically have a large amount of surface area, and that 24' trailer will also have a LOT of surface area, making them susceptible to handling problems caused by crosswinds and passing semis.
If it's got the V-10 and 6 spd torqshift transmission you'll be okay. Likely mpg in the 7-8 ballpark. Who you're buying the RV from is almost as important as what you're buying, not all RV dealerships are the same.
A super-C is a better choice if you want a coach greater than 29 ft. The Ford E450 (or equivalent) van chassis runs short of GVWR (and thus payload/cargo capacity) as the C's get longer. A super-C is built on a medium duty truck chassis that can handle a lot more weight, both in the RV body and cargo. Usually a longer wheelbase than the van too, and that should help stabilize that long trailer.
If you can find one in your price range there are other brands far better quality than the thor standard. Not every thor is bad but seems there are far more issues with most of their stuff than other brands
