I've never really heard too many good things about clear coating bare aluminum. Why not consider having them powder coated in clear? Might cost a bit more initially, but sure would last a lot longer. I'd have two concerns with spray painting clear coat on the wheels.
1) The paint flaking off sometime down the road.
2) The clear yellowing.
With that said, I clean my bike and wheels on a regular basis so they never really get bad. I replace tires about once each year, so when I have the wheels off, I use my Mother's Power Ball and give both wheels a "once-over." They look great and the time invested in minimal. That, plus I like diddle-frickin around with the Wing when weather doesn't allow riding. :wink: