What's the problem with aircrew pretending to be RAF Regt. In my time on SH, during exercises in the woods, we were often told to get into the trenches during stand to and defend the site.
As a young pilot I thought it was good fun - we were armed with 2 GPMGs per a/c with belts and belts of blank ammo plus we had night vision goggles so any "enemy" pongos trying to sneak up on the site were soon greeted with the mass chatter of at least 10 GPMGs. The armoury also wouldn't take back blank ammo so at endex we had inter flight firefights which would have done Rambo proud
HF