Car hauler trailers

I have a question here, there's a lot of old travel trailers out there that people would pay you to take away. Are their frames strong enough to turn into a car trailer?
Really it's in the axle rating in a lot of it..
I kind of like the idea of taking an old Dodge class c motorhome and whacking the back of it off and making it into a car hauler... You still get the van type front cab and it's the same small block Mopar 360 or 318 likely you have plenty of parts at home for...
Careful of boat trailers they're balanced completely wrong you would have too much tongue weight...