I lowered the wheel wells over the rear axle to 2" above the floor (I could have gone flat but I wanted the ledge for another purpose. The modification has provided no problems other than I must use cable chains rather than conventional snow chains. I'm big on doing cardboard mock-ups so I stuck together a bus floor/rear wheel mock-up using the axle up/down travel parameters I measured. I used the mock-up primarily to make sure that the wheels would clear the proposed floor level when one wheel was raised to the axle stop and the other side lowered to the bottom of the travel of the shock. In my bus even with a flat floor there was still over an inch of clearance between the top out most edge of the outer dually and the floor. As you'll see in the pics I kept what had been the inside vertical portion of the well and moved it to the body wall so I didn't have to modify the bolt on body fenders.
I would think the front inner fenders on your bus might possibly be removed. Make sone measurements of axle travel and maybe even a mock-up that includes up/down as well as left turn/right turn up/down travel.
Jack
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