Zen,
Okay, I'm almost done with the color coat. After I apply the symbol, I will start to apply the clear. My question is, how many coats of clear should I do until I can start sanding to remove the orange peel? I assume I'd do at least 3 coats of clear, lightly sand, and then clear and sand every subsequent coat?
On a solid body I'll do about 10 coats of nitro, but I haven't sprayed much enamel, only on metal stompboxes and various other objects, never on an instrument. You'll want enough clear coats to protect the color coat and provide visual depth - I doubt you'll need anywhere near 10 coats of clear enamel.
The deep mirror finish on instruments is usually done with lacquer, polyester (or sometimes CA) finishes. Not sure about enamels.
Frankly, my success with clear enamel from a rattle can over enamel color coats hasn't been great. On my stompboxes I used Rustoleum for the primer, color and clear, and a number of times I got wrinkles in the finish as soon as the clear went on, sometimes after the 2nd or later coats of clear. I tried with and without primer, baking the finish, waiting a week before the clear, etc. Best I can figure is that it had something to do with the temperature of the enamel and/or the box being finished, I never figured it out. My best results were when I used an automotive engine clear enamel over Rustoleum.
From what I know about enamel is that it isn't sanded and buffed like lacquer. Some don't buff it at all after the clear goes on. You could try wet sanding with 1500 grit just to level it and moving to a low speed foam buffer. Enamels can remain softer from what I've read so a buffing wheel may just drag the finish right off as it heats up the finish - be careful.
I'll bet folks with automotive enamel painting experience could give some good answers on this topic - I'm curious to hear how they would approach this.
At any rate, I would get a piece of scrap, spray it with the orange paint and then experiment with the clear + buffing steps before spraying it over your bass. Another option is to try a satin clear finish. It won't need to be sanded and buffed at all and may very well look real nice.