I have two suggestions, and both have already been made - so I guess I'm seconding; I am quite impressed with PooTwa's PUTW pickup. It has an excellent sound, is easy to install, and is quite unintrusive. You may spend a bit of time moving its location, experimenting for the sound you like best - but I found that placing it precisely the way the instructions suggested worked best. You will probably need a pre-amp - but you've got good choices on the market there.

The other suggestion I want to second is the fishman rare earth pickup - again, it is quite unintrusive (no or little cutting is required) and you might well be very happy with the sound. I use one in my 000 Santa Cruz. It does have a bit of an 'electric' sound - but the sound is so pretty, and the mix of of acoustic guitar qualities so strong that I find the sound excellent. I must admit, it was not the sound I was going for, but once I heard it, it was what I wanted. I love it. I use my 000 for finger style picking, and this pickup works very very nicely for it.

The good news is, you have some great choices. Good Luck!