Well, i graduated last year as a graphic designer and now I'm studying product design, so I could probably help out with that, be sure to let me know.
about the box, at first I thought it would of been more obtrusive, but it seems it can be kept pretty low profile (as in inconspicuous); at least on an RG type guitar where you got this big trem that sort of makes the box blend in. On a Les Paul it would probably look a bit more out of place, but I really don't see why you wouldn't or couldn't build the circuitry into (inside) a Les Paul, after all they put the sustainiac in there too, and that's a fairly big circuit. Of course you'd still have the problem of the extra controls (that's why I thought of putting them on a separate pcb or something, so you have just the controls on the outside and everything else inside).
So, although I like the idea of a custom tailpiece, I wouldn't put too much effort into it right away. Somehow I think it wouldn't be very cost-effective.
About the glow strip, at first I made a graphic where the driver was completely in chrome (can post it if you want), which was a bit more classy looking and i liked that one better. There's a trade-off here: you'd want your driver to be unconspicuous (given the idea of hiding it in the pickup ring); on the other hand you'd want a striking look, making people go 'hey what the hell is that, I want one too'...
I was actually thinking of leds on the bottom of the driver, that could light up the area underneath the driver (think of neon lights underneath cars). You'd probably have a little gap between the driver and the surface of the guitar anyway, becase of the height adjustment screws.
I'm gonna go do a bit of research on rechargable batteries now
see ya, Tim