For handling start low cost.
Get an axle weight at the local scale loaded like you travel. Adjust your load to proper limits. Look up the tire manufacture inflation table for your weight and set tires to that amount plus 5 pounds.
I think on yours you can do what is known as the "Cheap Handling Fix" AKA CHF. Do a search for it and you will find some videos. Not hard to do.
While you are under there look at the rear sway bar bushings. They are likely toast as until about 2012 Ford used a soy based product that rotted away. Also the bushing mounting bolts have a habit of loosening and then causing the bracket to break. Replace with poly bushings. Head to eBay and get them from
https://www.ebay.com/itm/Ford-F53-Class-A-Motorhome-chassis-REAR-Polyurethane-Sway-Bar-Bushings-1999... He make top quality ones.
Then when you install them tight tighten to 66# with Blue Locktite.
Then you can start down the hardware dollar path.