RE: This is gonna be tough...
It looks like the CG would be a little bit aft of the spot where you show the wingtip seams meeting the leading edge of the main wing.
I've been thinking about a similar project but a little different. Capture a hawk or a eagle and rig up a harness to control it's head with a couple servos. It should work like steering a horse, it'll fly where it's head is pointed.
Once the bird gets all trimmed out and used to doing pylon laps, then the idea is to suit up little squirrel monkeys like jockeys to ride the birds around the poles..
so, you can see how we have basically the same idea going here........