Which style of bellhousing mounts does your truck use? The kind that bolts to the side of the bell or the kind the bell sits on? If it bolts to the side, could you slot the bolt holes some to gain the clearance? If it's the kind that it sits on, could you make new "thinner" ones?
Just throwing out ideas,
Scott
Also, when I rebuilt my 4400's floor and trans cover, the hump on the trans cover was rusted to the point that it required replacement. The old hump was almost the exact same size as a 9" X 13" cake pan. So I went to Wally World and bought the heaviest guage cake pan and welded it to my trans cover and no one is to the wiser. Maybe you can make your own cover from the baking isle of your favorite department store.