There is an "easy" way to measure AoA if you have a decent inertial system.
The inertial will portray actual flight path in space on something...... a HUD, an FD or whatever. It will be related to your airframe axis depending on the display. But the biggie is you can compare the actual flight path with your plane's axis. The difference between your longitudinal axis with the other two axis combined will show your AoA - flight path related to wing angle.