Any chance you can add a Flying vehicle HQ, Landing pad maybe? Not sure his helicopters can land so, may be an incompatible idea. Maybe you can work with pique
to have them create a landing HQ for aircraft.
Also, maybe add other mod vehicles to your HQs. There are now Heavy Trucks (not as big as the huge haulers) as well as some heavier excavators and the TREX hauler (really big loose hauling vehicle) Might be simpler (less updating later) to search the game for any vehicles of a specific class and just auto add them to an HQ. I have not checked it in a while to see if you already did this, i just remember using mod vehicles that ignored your HQ.