My Fleetwood Prowler has a I beam frame and it has a Class IV hitch welded to it. I have pulled around 3000lbs of boat for many miles. I think you will find most states require a brake on the second trailer if it is over 3500lbs or so.
I was thinking about pulling a 21ft 4400lb Travel Trailer behind the 5er but adding the extra 7 pin plug and brake controller has got me doing more research than action. Wire gauges, current draw, etc. all seem solvable but I just have not made any headway on the work part.
One more thought to consider. Will 600lbs hitch weight on the rear of the 5er frame make the 5er pin weight to light and lead to a squirrely tow.
