I think in California the double tow can not exceed 70-ft. I’ve seen a few people towing a boat behind their 5th wheel. One I met was a retired fireman who used to drive in the far rear seat of a hook ‘n ladder type fire truck; he was the one that told me it was 70’.
Besides the weight capacity of the rear bumper, which I have been searching without success to find out what mine is, towing anything on the rear bumper, or even having a bike rack or cargo carrier on the rear bumper, subtracts from the available towing capacity of the TV and adds to the GVWR of the five’r. In short it is easy to go over that GVWR or TV towing capacity when towing from the rear of a 5th wheel.
If anyone knows how to find the weight rating of a 5th wheel bumper I would appreciate your letting me know. I was going to put a bumper mounted hitch on the rear of my 5th wheel to accommodate a cargo carrier. I have a 2012 Heartland Prowler Sport 5th wheel and I was talking about this on the Heartland Owners website an a moderator posted this in reply to my inquiry:
“Thank you for your post. Lippert will not give us ratings for the rear bumper. The only parameters they tell us is that: "if you tow from rear bumper, this could void the frame warranty". This is the same for all frame manufacturers, as Lippert supplies most of the industry with frames. In this case, common sense will prevail. Please bear in mind that any weight added to the bumper will reduce hitch weight. You want hitch weight!
Hope this helps.
Bryan Walczak
General Manager - Heartland RV