A helicopter bot is definitely feasible but I don't see any way you'd get around coding your own AI for it. It would end up being easier than trying to jury rig hole bots into doing anything correctly, but would still be technically challenging.
A bot would seem to be the simplest solution, you could give it a lot of air control and use setMove and setAim methods to move it around in the sky. I can't remember if you can change jet speed, but you could easily control a bot's altitude by manipulating it's velocity directly. This would be smoother than using a vehicle but you would be sacrificing the ability to rotate it on more than one axis, though if I recall correctly there is an animation trick used in the skateboard add-on that you could use to change the pitch of the helicopter.