An A gasser built on a the 16,000 GVWR Ford F-53 chassis, 26,000 GCWR, COULD have a 10,000 pound towing capacity, if the RV manufacturer did not do something to decrease that. You likely will not find that as the RV maker's tow rating, simply because they do not routinely install 10,000 pound hitches.
There were Jayco, Gulfstream, Bigfoot and Fourwinds (Thor) "Super C" models built on Class 5 and Class 6 GM Kodiak, Ford F-series, Freighliner M, and International chassis. Some of these, at build weight, would have sufficient unused GCWR to tow 7500 pounds.
As a class, I think they are mostly gone from the market now. The GM chassis is no longer made, and I don't think International is in that market segment now, either. Jayco moved the Embark to the Freightliner M series, and is now building a Seneca on Freightliner (that was their brand on Kodiak), which should be less expensive than Forest River's Dynamax line, but the available models might be too big to have the towing capacity you seek. You run into the "too big" issue also on the lower-end diesel pushers if there is too much motorhome on one of the lighter chassis models.
