LR Baggs M1 pickup
I very highly recommend the L.R. Baggs M1 soundhole pickup, specifically the passive version, which I have installed as an upgrade to my VAMD-02. After doing a lot of research, I simply can't think of a better electronics solution to use with a Voyage-Air.
The M1 is a stacked-coil design, but with the lower hum-canceling coil suspended inside the pickup's shell in such a way that it vibrates with the body of the pickup itself. That adds the vibration into the signal. The result: this magnetic soundhole pickup genuinely senses the sound of the wood, similar to a good under-saddle or under-bridge pickup. Not just in the second-hand way that magnetic pickups sense only the strings, but the strings get influenced by the body. The tone can compete with any under-saddle or under-bridge pickup system.
You can also adjust the pole-piece heights for each string, for volume balancing. When you properly set it up (and put some time into the fine adjustment), it really can sound like your acoustic guitar, but louder. Maybe the only way to top it would be a multi-source setup involving an internal microphone — which might not be as friendly to getting bounced around in the Voyage-Air backpack.
Finally: here is why the passive version of the M1 is ideal for a Voyage-Air. This pickup comes with a cable that can hang from the soundhole, and can detach from the pickup when its not in use. The passive version also has a groove on the bottom of the pickup, to secure the cable for stability. The active version does not have this groove, as that space is taken up by the battery, and therefore the active model is best suited for a permanent installation with a hole drilled for an included jack. (The jack installation can also be done with the passive version.)
Of course, you would have to carefully maneuver your hands around the strings in order to plug the wire in, and get into the groove, and to undo the whole process each time — but this is not a problem at all when you fold the neck over and get the strings out of the way! If you're in a place where you're going to plug in, then you can simply do this setup when you first take the guitar out of the backpack, and then later remove the cable when you put the guitar away.
For this LR Baggs M1 passive soundhole pickup, you don't need to hire a technician or do any drilling at all. You can keep the pickup in the guitar at all times, and then add or remove the cable as needed. And if you ever buy another guitar, like a higher-end model, you can just unscrew the pickup and transplant it over to the new instrument.
Finally, if you wanted to have a permanent installation for your guitar, with a permanent jack and an onboard pre-amp control, etc, the M1 is a great place to start.