JSF-TC great work - really nicely done. I'm enjoying reading your build thread. I had a thought about the blowing - had you thought about using electric ducted fans and some careful duct design to blow air?
Edit: Have now completely read the build thread and have to say I think that there is still room for investigation in your hstab servo calcs, however you are watching the servo current, so, it can't run away from you. If you were feeling brave I suggest do some high altitude runs at approach speed to look at where the stab runs out of power with deflected flap angle.
I would be looking to calculate the centre of lift of the stab plane with and without stab flap deflection to make sure you are using the longest moment arm for your servo torque calc - catching the deflected distance change is good, but might be only one side of the story.
The deflected stab flap will reduce your stab plane stall angle as a flap would on a mainplane. The initial guess with this is to draw a line between LE and TE - the angle that line makes with the stab chordline will give you an effective stab plane operating angle of attack.
The other thing I would look at is whether your servo actuator rod is stiff enough not to bow out under combined load of the servo and the stab pressure load - this would not necessarily increase servo load (hence not seeing the servo current go up) but also reducing the effectiveness of your hstab (because its at a lower deflection angle than you think). I can't see what your stab actuator rod geometry is.
I do a lot with the UAV world in and out of professional life and it is interesting to see the differences in minimum requirements - for example all control surfaces should really have redundant actuation. Telemetry and monitoring is also another difference between my RC buddies and my UAV buddies (I sit in both camps!) My Cube Black, HERE GPS and Mauch power electronics collect masses of data for me, all in one place. I know you have some of that data with the JETI system, but there is another level you could go to - and you could use the CUBE Black as pass through or as a basic gyro (FBWA mode), up to and including full automatic mission from take off to landing. I know one F3A pilot that uses an ardupilot flight controller and GPS just to log his flights for review.
Anyway, just some comments!