Chevy/GMC bed height

My 2020 CC standard bed RWD measures 59 1/4" at the rear bed corner. When I looked for new truck I was hoping the RWD would be lower than 4x4, but not the case anymore. Both measured the same bed height. The dealer gave me such a great deal back in May because of covic-19 they were having a hard time selling inventory, I bought it. It had the 5th wheel puck system, so I bought the Curt adapter for my Q20 hitch. I hooked up my Sprinter 5th wheel and started laying boards under the tires of the 5th wheel. After several attempts, I had 4" of wood boards to get trailer to measure from ground to frame the same, front to rear. I found a company in Canada that makes lift kits and bought 2 set, 1 set per axle, 3" lift blocks. Trailer still not even front to rear so I changed out my 15" rims to 16" rims and had Goodyear Endurance ST235/80/R16E installed. It was finally equal front to rear. I've toad it over 4000 miles now and it's been great. Love the truck, but it took some work to get trailer level. One other thing, I kept my 6" clearance between bed rail and bottom of 5th wheel.