I would try to keep the Weight Distributing Hitch...and would call the hitch maker to see what they have to offer.
My 10,000LB Equal-I-Zer came standard with adjustment for over 6" and I know they offer other/different shanks:
This is a common problem on larger frame tow vehicles with all trailer types including dolly's and flat-tow tow-bars.
And, 2 options I have seen:
1. A doubled receiver (2 receiver crossbars at different heights on the back end of the truck).
2. Modified step-up trailer tongue.
I would guess they both were owner mods, but looked to be done professionally.
Kim and Steve, Mustang LCDR (Ret), '07 Damon Outlaw #1193
I have seen gross intolerance shown in support of tolerance, Samuel Coleridge
WE LOVE OUR OUTLAW RV