NMC
What exactly would be the point of these aircraft? Just to get airborne and not get killed?
Whilst they would be tricky to shoot with an A-A gun if they were doing their best Aeros display that is not really how BFM works. Especially not with missiles and a little thing called tactics.
Also, the kind of gun that an Extra could carry would be pretty puny and not really worth the hassle. You’d be surprised at how A-G gunnery can be very up close and personal and the kind of calibre you’re talking about with it’s associated range would leave the aircraft open to all manner of ground fire.
So basically if you just wanted to take off and buzz around seeing how long you could live I think you’d be better off finding a better hobby.
Finally, as has already been mentioned, if all you want to do is saturate the sky, use drones.
BV