[JRTJH]

I'd suspect that most receivers are a "custom fabrication".

Curt Hitch has two models available that are "bolt on" hitch assemblies. BOTH of them are available at outlet sources like Amazon or EBay for less than the MSRP.

If you elect to install one of either type, be sure that you don't exceed the actual trailer frame weight restrictions. The "rules of physics" apply to weight capacity (only as strong as the weakest link). You can install a hitch rated at 15,000 pounds on a YUGO, but that doesn't mean the car is capable of supporting or moving that much weight. It's the same with trailers. An "Ultra-Lite" component frame (such as used on the Passport line) are not "substantial frames" with conventional I beam or C channel frame rails. They are similar to the "uni-body automobile" concept and many will not support substantial weight at a distance beyond the axles (the axis point on the frame).

It's best to talk to someone who has experience with installing hitches on your type travel trailer frame. This isn't a "Saturday afternoon with a good buddy and a case of beer" type of modification.