This is a topic I've been interested in as well. My idea is not to necesarily get either a full electric or acoustic sound but to explore a spectrum in between. On my last electric build, I made a body about two inches thick with the sides carved out of a solid piece. I've decided, as was already stated, that this was a big waste of wood and was quite hard to do. I've since been finishing up my first acoustic and have struggled through the bending and will do the sides like this from now on. For the electric, I made the top thicker (about 4mm) and of bulbinga with no bracing. I put two electric pickups on and a sound hole up on the top bout. Under the bridge area I left a block of wood to mount an electric bridge, but it does not go to the back. My theory was to get some top vibration and to have a sound hole to relieve the internal air presure. I like the way it turned out. It is fairly jazz sounding on the neck minihumbucker and is probably more towards the electric side of the spectrum.
What I find is, that most of the common magnetic pickups will sound like an electric guitar. A very interesting pickup though is the Dean Markely sound hole pickups. I've had one in an acoustic and to me it sounds better than peizos I've heard. These pickups are voiced for bronze strings . I keep asking why there doesn't seem to be a pickup like this in the form of an electric guitar magnetic pickup. If you had bronze strings on a semi hollow guitar and a pickup like that I'm sure it would be close to an acoustic sound. One of those at the bridge and a big snarly humbucker at the bridge might do it.