**Not for the Faint-of-Heart**
My only acoustic is an old Ibanez lawsuit copy of a SJ... not in great condition, but a great campfire guitar. I wanted to experiment, so I created a 'floating centreblock' of 1"X3" inside the soundhole, with an old Supro / National singlecoil attached. (those pickups were mounted directly to the body via drywall anchors anyways, so it made good sense from an aesthetic and mechanical standpoint.) I added a 250k volume pot to the face of the guitar... just drilled a hole and mounted it in easy reach, and then mounted an end-pin output jack. Sounds amazing, with electric .13's, or .13 acoustic strings. (a little more output with electric strings... the brass cores of the acoustic strings likely doesn't register quite as well with the magnetic pickup.)
I know, the purists are going to tell me that I've ruined the resonance of the face of the guitar by mounting the pot, and obstructing the soundhole... but if you could hear the snarling Elmore James pouring out of my Champ 600... you'd have a smile on.