Hi Pegasus,
Awesome project!
A few others have done D/F harriers in years gone by. One or two featured in UK mags, maybe even RCJI. The ones I saw used bleed air from the fan in oversized ducts (+- 1.5 x 1.5 ") to tail and wingtips and using servos to direct thrust. Seems to have worked for them to some extent. I think traplet has one on video as well. I would think for best result the centre of lift and gravity should be close also in the vertical axis to be as effective as possible and all mass as close as possible to the CG to reduce the innertia in rotating around that axis.
As far as control goes a fast acting control system that can correct when the required reactions are still pretty small would have a beter chance. Old flying buddy now working in the US for Athena has done just that with his VTOL drones. To date he is the only one to get a robot to run on a single wheel without falling over. Secret was a heavy reaction wheel for control, similar to what we are using on our micro sattelites.
Cheers
Andre