After thinking about this for a while, I finally got around to making my own spacers. I used some 1"x2" box steel, welded a stud on one side and used a longer bolt for the other.
The hardest part was breaking all the rusted bolts loose. The spacers on the skid plate lowering kit had fused to the bolts, and I ended up cutting a couple of them off. Good riddance!
Things turned out good. There were no clearance issues, and no drive line vibrations.
More pics available on request.