The VGs in pic 3 are on the LE of the elevator.. Designed to be inside the hinge gap and out of the airflow at cruise, and exposed to the airflow at full up elevator. This was developed by stolspeed and recommended to Zenith. JG recommends building a tailplane with a symmetrical airfoil similar to the Savannah if you are building from scratch, but I don't think Zenith will support you on that. The VGs aren't needed on Savannahs.
I like the idea of the adjustable seats... The more I look at this thing, the more I want to buy the plans! I'm even beginning to think I don't need to design my own aircraft to get the performance I want... This will come close enough.