Fifth wheel height

Those are basically 12r22.5 tires, dropping down to an 11r and the lower base should get you there if you are on 8 bag, if you have the heavy nu-way I know that sits a little bit taller, you kinda bought the wrong spec truck for what you want

 

Holland has low 5th wheel saddle , easy to swap , you can drop height atleast 1 inch.

 

What does it have for gears, tall rubber and heavy spec usually means shorter rears, drop to low pro rubber you might be screaming on the highway

 

Buying a heavy spec truck to pull a box is like buying a hammer to loosen screws.

 

Look through fifth wheel manufactuer(Holland, Fontaine Jost etc) websites? Quick browse of Fontaine site shows 6 3/4- 10 1/4 mounted height

 

Get the Holland low mount risers. Pop the pins out, take plate off, grind stops off one end of the sliders, reverse, weld stops back. Most Trucks I’ve seen with low mount, and 24.5 lo pros are at or less that 48”. Might not have to change tires at all.