Considering how long the question of making GSX to work better in full cockpit simulators is discussed here, it will probably never be done.
So I just decided to resolve it by
brute force.
Like others that posted here, I have full Boeing 737 cockpit.
In addition to 3 projectors there is the 24" monitor where I have P3D window with "Panel Display Only" option set.
P3D menu and GSX menu show up there and not on the projectors' views.
In my cockpit I also have two tablets - on CPT and FO sides.
So what I did - I installed web camera (Logitech C920) in front of the monitor. The camera is connected directly to FO 10" tablet.
This way the GSX menu is visible in the tablet screen and I am able to see and operate it from Captain's seat.
I call it "stupid GSX trick".
I tried Air Display and some other wireless solutions, however found the impact on main PC performance not acceptable so far.
http://elephantair737.blogspot.com/