I too own a 2000 Rexhall Vision 25' F53/V-10.
The frame is actually shortened in the middle as the factory frame is too long for this length body. I don't recall the rear having frame extensions. The rig came with air helpers which I run at 45 psi all the time.
I do recall that Rexhall really messed up the driveshaft angles and phasing due to the frame shortening, but that's fixed now!
I tow a 20' Haulmark car trailer at near 6500# full up. It has 4 wheel electric brakes, behind a Prodigy brake controller.
The max gross combined weight is well under factory specs. Although the hitch is rated at 5000/500, most hitch manufactures will uprate
that if used with a WD hitch. I opted for a Pro Series square tube trunnion style WD hitch with built in friction pads.
When I tried the combination without a WD, it was white knuckle driving. With the WD hitch and its anti-sway capabilities it's pretty good, but you have realize you are still driving something with almost 50 feet of flat panel to a side wind.
Still, the combination is stable, the RV rides flat, and with the V-10 I can still climb mountain passes as well as some 36' class As since we weigh about the same.
It brakes as well as the 18 wheeler who did a panic stop in front of me last month.
I run at 60 mph on the flats and only when cresting the many, many mountain passes in Washington state am I down in third gear. I might have hit 2nd gear cresting Snoqualmie ...
Coming down most passes is not an issue.
I do note that the trailer is really close to the rear walls of the trailer when turning and that you should consider a trailer with an extended front tongue if buying new.
I've run this combination for almost 5 years.
There is no accelerated brake wear, the engine still runs strong, and the trannie still shifts well.
I do change engine and transmission fluids before each race season as well as keeping religious track of tire pressures on everything and trailer wheel bearings/brakes.
I carry two spare trailer tires and one fully inflated RV spare as well to avoid calling Good Sam.