No, never heard of, never seen. And pretty sure, it would be forbidden. We have very strickt laws. Every "modification" on a vehicle needs to be approved by officials. But it sounds interesting. Got pics?
I'd be afraid to drive behind vehicles with trailers where you live!
I've had a trailer pop off the ball once, the bolt that holds the coupler in was loose and fell out, luckily I was on a road in the middle of nowhere, It just came off the ball and dragged behind me. A friend of mine wanted me to haul it to his new place.
I always make sure everything is legit now!