I also think you can learn a lot by seeing what's been done.
Probably the most widely purchased is the Taylor T5. Building on the Taylor Expression system, it uses a single body sensor located an inch or two below the bridge, an acoustic mag pickup buried beneath the fretboard, and a stacked humbucker in the bridge position. (It looks like a lipstick pickup, but it really is a humbucker.) This is what I play most of the time, and in my humble opinion, it's better at electric tones than acoustic ones. Run it through Taylor's K4 equalizer (a $500 investment, unless you get a deal), and it gets better, but still not awesome.
An interesting variation is the Crafter SA. Crafter pretty much copied Taylor's design, but they put in an LR Baggs piezo pickup system. Reportedly, the acoustic sound is better than the Taylor guitar it copies, and it's much cheaper.
The thing about a piezo pickup that I find interesting is that it sounds pretty similar from one guitar to another. A cheap guitar and a high end guitar sound pretty much the same. That's why piezo bridge saddles sound good. As long as something's vibrating, you get a pretty good piezo sound. That brings me to my next example.
The Parker Fly is, I think, the best representative of a hybrid that uses a piezo pickup successfully. It's an electric guitar with piezo pickups build into the bridge saddles. Most of the big acoustic pickup builders are now making bridges just like this. Because these are typically six individual piezo pickups, you can run it hexaphonically into a synth.
A poorer attempt at the same thing, in my opinion, is the Ovation VXT. It also uses a piezo bridge, which is fine, but I guess I expect more from a company that's been making acoustic guitars for as long as they have.
Then there's the Anderson Crowdster Plus. To ears, this one actually sounds better as an acoustic than it does as an electric. A lot of that is probably because this is the only one mentioned so far that uses bronze strings. They built a humbucker designed for bronze strings that's unlike anything else I've heard of.
Finally, there's the Ibanez Montage, which is your basic acoustic guitar with a humbucker stuck right where you'd expect the soundhole to go.
I think it's helpful just to search for each of these on YouTube and see what they do. You can learn a lot that way. Obviously, there are a lot of hybrids out there I didn't mention. But that covers the major types of hybrids I know of. In the end, this is mostly experimental stuff. Like Rich says, you just have to have fun building something, and see what it sounds like when you're done. If you'd like me to point you toward some interesting reading I've found, let me know. Can't wait to see your build! Since you do build so much faster than me, I'm sure I'll learn a lot from it your build that I can apply toward mine.
-Dave
P.S. Oh yeah! Final example: Mikro's reso. From what I've gathered from him, a cone is a great substitute for a traditional soundboard.