Sanding the outer surface thinner is the way I do it. Keep in mind you'll need to somehow make a ledge inside the holes so the new grip screw head doesn't protrude above the surface. Blindhogg sells a drill bit that does this perfectly at www.blindhogg.com
And also now that I think about it...3/32" is VERY thin for thin grips - I believe the standard 'thin' grip is 5/32". If you go too thin you wont be able to find any thin bushings/screws that will fit correctly.
I have successfully sanded down two different pairs of grips;
Springfield Loaded grips that were way too sharp in the checkering dept! Used a combo of my dremel tool and hand sanding. The Dremel took the excess wood off until all that were left were faint indications of the checkering lines, then I used 120 to 220 to 320 grit sandpaper. Voila! Then several coats of tung oil and I had thinner smooth nicely figured grips.
Sam process for my CZ 97 grips, they don't have the nice grain that the SA cocbola had, but still nice (walnut).
It's not that difficult, just take your time, remove evenly over the whole grip surface when using the Dremel. You don't need heavy pressure, just a light touch with the drum sander attachment.
I'll post a pic of the SA and then the CZ.