I have just recently mounted my 2000W Honda gen on the rear bumper of my 5er. I made a 1.5" receiver and welded that to the top of the bumper. I then made a square frame out of 1.5" angle iron that's the same size as the base of the gen. I welded a stinger that runs the full width of the frame. I slotted out the angle iron on the front (5er side) and ran the 1.5" stinger thru the slot and extended it out enough to fit the in the receiver. I then made a bracket that will accept a padlock to lock it to the 5er. I have a tension bolt on the top of the receiver to keep it solid. I mounted the gen to the frame by removing the 4 rubber pads on the bottom and using longer bolts, bolted it to the frame. I then tack welded 2" wide plates on the bottom of the frame to cover the bolts. That way no one can unbolt the gen from the frame without going thru a lot of work. I also used allen head bolts to make things tougher.
Gen only weighs about 60lbs with all the frame added.
I notice zero difference in towing. I also have a Northwood MFG built frame so it's quite a bit stronger that the average trailer frame. At least as far as the bumper is concerned. NW mounts the spare on there as OEM so they have to figure it's beefy enough.
![](http://i1274.photobucket.com/albums/y422/goducks13/DAMONMILLER-PC/Pictures/IMG_20170619_075332520_HDR_zpshlmpl7f6.jpg)