It looks great! I especially like the look of the back. The electronics look interesting as well.
An F clamp should be fine, but I prefer a one handed clamp like this:
Attachment 44191
It will allow you to hold the neck and body together with one hand and clamp with the other. It's possible to do that with an F clamp, but you don't have to be as well coordinated with the other type ;-)
I will be very interested in how you mount the electronic components. I have never tried to install a pre or battery box on a semi hollow, so please take this FWIW...which may be nothing at all ;-)
If the pre is small enough, you might be able to fit it through the hole you would need to make for a battery box like this one:
battery box
Attachment 44190
If that works it would minimize cutting on the back of the guitar. YMMV, but I have not been able to get even a full sized pot through the F-hole on my ES4-B. If the F-hole is the same size I don't think the battery would fit through even if there was a place to mount it. That said, the forum has often shown me that there are more possibilities than the ones I have thought of, and I will be interested to see what you come up with!