Thor 8000 lb. hitch?

To increase the hitch weight you need to strengthen the frame in back, here is some pics of my frame in back, note the 6x3 square tubing going in from back all the way to factory frame and three 4 inch round tubes welded to 6x3 square tubes and welding to hitch.

I belive forest river has 7500lb towing cap but a 500lb tongue weight.

Here's a Ford document on frame stretching that goes back to 1991, with a number of revisions over the years. I would imagine all, if not most RV builders, have been building to those specs all along, although they have for CYA reasons been downgrading what Ford says the unaltered vehicle is capable of towing.
It's good to see that some of them are now rating the vehicle to tow up to Ford's rating.
As j-d pointed out tongue weight on a stretched chassis is another issue . My 2014 Itasca has a 5,000# hitch and reading the owner's manual, it's hard to figure out what they actually rate the vehicle to tow, but it is quite clear that they do limit it to a 350# tongue weight.

My understanding of frame stretching is that Ford published a standard that the motorhome builders are following. And that the standard if followed preserves capacity and warranty.
That said, I have two observations:

1. There's still a lot of bickering when it comes to chassis warranty issues like driveshaft alignment and balance.

2. There may still be a down-rating of hitch capacity. It only makes sense that a hitch 10-12-feet behind the rear axle should not be expected to carry the full rated tongue weight. Not uncommon for the max towing capacity to be for flat towing, which applies essentially zero weight on the hitch.

So what I'm saying is the "7500-pound rating" may be for towing a vehicle four-down or on a dolly, and does not allow for the tongue weight of a 7500-pound trailer.

I've also read that Weight-Distributing hitches are not recommended for stretched-frame motorhomes.

Sunseeker is putting a 7500 lb hitch standard on most of their Ford Class C's.

Looking at the specs. , they're saying that the E450 has a 22,600# GCWR,(up from the 22.000# GCWR) along with the same 14,500# GVWR it's had for a number of years. That leaves a tow rating of 8,100#. They're obviously not down rating the GCWR as most manufacturers have been doing for so long. I"ve seen Ford's site that says it still has a 22,000# GVWR, so I don't know where the extra 600# is coming from unless Ford is doing something special/different for them. :h