I was just looking at hitch extensions as I need little more clearance from the motorhome to load/mount a spare tire. I have not bought anything yet, but was amazed at how differently a hitch receiver extension is rated as opposed to a fixed ball mount extension. It is not because one is hollow, they are both hollow.
Here is a hitch extension that gives you an extra 12":
https://www.etrailer.com/Hitch-Adapters/MaxxTow/MT70024.htmlMaximum weight capacity: 3,500 lbs
Maximum tongue weight: 350 lbs
Note: Using this extension will reduce your hitch's weight capacity by 50 percent.
(So I would only have a 2500/250lb hitch?)
Here is a similar extension in the form of a fixed ball mount:
https://www.etrailer.com/Ball-Mounts/Hidden-Hitch/80232.htmlGross towing weight: 6,000 lbs
Tongue weight: 600 lbs
(Of course, I cannot exceed my 5000/500lb hitch rating)
What makes this important for me is that I am not just flat towing, but sometimes towing a boat. So as I am now picking out a towbar, I find myself limited to the vehicle mount variety with a ball coupler. This rules out some of the popular braking systems towbars like the ReadyBrute which only come in receiver hitch form.
2007 Tiffin Allegro 28DA