It seems to be fairly common knowledge that most planes, gv's and ships were open to be modified once they reached their theater of operation - military personnel can be very creative when it comes to finding ways to being more effective or surviving!! I thought it might be nice if field mods were made available as a perked option for un-perked vehicles and planes, ie a B-17 20mm perk option, etc. I am not an expert as to what was modified and how, but there certainly seems to be a lot of expertise on this board as to what might be made available.
Might make it a bit more interesting when you encounter a con or GV, not knowing what type of mod you might be facing.