A minor update, for those of you who were interested:
My Gecko #11 now has a second pickup!
Here is a picture of what it looked like initially. It had a single Q-Tuner pickup in the "sweet spot" position:
After playing this for a while, I decided to add another pickup near the bridge position, for additional tonal variety.
First I removed all the hardware (as well as the neck), attached the pickup template to the body with double-stick tape, then started removing some of the material with a drill. It looked rough, but it got the job done.
After a few passes with a router (equipped with a template bit, of course) I made it look like this:
Notice that the bottom of the cavity doesn't look that nice. This is what happens when you buy a cheap Skil router with a motor that slips down on the base as you use it. I had to keep stopping, re-adjusting the base, clamping it down, and resuming the work; however, the result is messy.
But once I applied the adhesive copper shielding and installed the matching Q-Tuner bridge pickup, all that messy work is hidden.
I don't have any pictures of the bass with its strings on, but I do have to say that it sounds fantastic with the second pickup installed.
I also did a neck swap. The original neck was maple with a wenge fingerboard. The new neck is wenge with a ziricote fingerboard. I think this is a better tonal match for the Q-Tuners; plus, it looks nicer against the walnut body.
Oh, by the way, I'm going to be taking that Skil router back to the store for a refund.