Hey Subpar ,
A wise and experienced mission and campaign builder once told me to
spend my time trying to use what the game actually does to build campaigns and missions ;
not waste time wishing it did something different than it does ( that's for the modders out there
to attack ).
So , to address your problem , if you accept that the game gives you no means of measuring
successful aerobatic performance , what else does it do that could measure progress as a cadet pilot ?
Think of things like navigation ( to a time limit , in poor weather , using beacons , base to base to base , etc etc ).
The game be manipulated to score for all of these do all of these.
Get your cadet to lead an element or a flight and get them to attack a training target.
Attack the target with strafing and dive bombing - could be two separate missions , or one combined.
Give your cadet a limited fuel load and have him make a flight that is at the hairy edge of fuel consumption.
Have your cadet land within a limited and defined area of the runway.
These are just a few thoughts that have come to me since reading your post - I am sure you and others
can easily come up with more.
Good Luck.
Kopfdorfer