May i make a suggestion, here you are trying to farm the insurance field.
If you wish to reduce the ploughing and increase the yield;
Do as nigelh suggests, ban the practice autos for the participating aircraft,
but insist on all participating pilots to be proficient and current in them, in someone else machine.
I.E A flying school whose business it is to hire aircraft and instructors to teach and check proficiency at, amongst other things, safe EOL's.