Couldn't you just fab up some shorter brackets? From pics it almost looks like you could lose, maybe an inch of length. Since it's hex heads, you could use a wrench to install/remove and not fight a screw driver. More negative offset wheels (if you could find them) would be way too expensive...
For years and thousands of miles, my '97 F350 7.3L Power Stroke has proven itself a capable tow rig. With an 11' Lance camper aboard and flat towed my 80 as well. It would've been definitely better on a trailer, but I had no place to store a trailer when not used. I sold the camper, but still...