I didn't realize you could tow a 5th-wheel trailer with a regular hitch. Is this true?
There's an old saying "Just because you can, doesn't mean you should."
Every one of these setups I've seen is "home made." Some just look more professional than others. Ask yourself, when was the last time you saw an MANUFACTURER of 5th wheels say you can pull one of their trailers with a regular hitch? Like, NEVER. If it was a prudent thing to do, I would think that manufacturers would be all over this as an option because it would open up their potential buyer list to a whole new group... like SUV owners.
No way, no how would I ever tow a 5th wheel with a setup like this. There are too many shark lawyers out in the world just waiting for someone to do something stupid. And since you'd get zero support from the manufacturer.....
Your "mileage" may vary however.