Bionic Man wrote:
I tow tandem with my fifth wheel. Quite a bit to consider doing this.
In regard to your question, I would suggest custom fabricating a hitch, and reinforcing the frame up to the axles. If you aren't a welder, find someone who can do it.
Even a little trailer will act as a fulcrum, and little bounces in the road will transfer to your TT, and up into your tow vehicle. It is important to adequately support the hitch.
X2
Plenty of people on forums have tried putting hitches on unimproved bumpers to put a platform on for their generator or cooler or bikes. As Mentioned, the leverage puts significant stresses on a bumper that's not made for it. Go custom and attached to the frame solidly if you go this route.
Also remember, your giving up the ability to back up more than a few feet when triple towing with ball mounts so pick up parking spaces, fuel stops carefully. Many have a hard time in many gas stations other than truck stops (flying J's, Pilot's, etc.) with a long rig. You will be joining that group with a triple tow.