I had the same issue when I switched from an F150 to an F350. I ended up having to lock my Sidewinder so I could move it up two more inches, and finally replaced it with a MorRyde pin box at the highest position. I had also replaced the MorRyde CRE3000 equalizers with EZ Flex and wet bolts. Turned out the RV sat lower with the EZ Flex, so I swapped back to new CRE3000s when I got the pin box. Perfectly level after that.
2015 F350 XLT PSD CCSB SRW, Andersen Ultimate hitch
'12 Cougar High Country 299RKS, Mor/Ryde Pinbox
1/77 Armor Bn, 5th Mech, I Corps