I mean at one point I just said ♥♥♥♥ it and spawned superior anti-air tanks all around the base and they were taken out before the helicopter spam was over.

1. The RHS armored vehicles can be extremely difficult to destroy. I found a one-shot spot on the back of the M1 turret, but the M2s seem almost invulnerable. The vanilla vehicles are relatively easy kills but will murder you instantly from 300m if you give them a chance. Both cases could do with some balance tweaks, IMO.

2. The static AA guns are pretty good at killing helicopters if they get the chance, but if you stack a bunch on a base then they'll get wiped out with one bomb. Should work better if you place multiple checkpoints around a base and put the AA guns there instead, although I'd still expect the static defenses to get wiped before half the waves are done.

I stopped some airfield attacks solo on vanilla by spending all my time buying and repositioning AA trucks: That might work with RHS too but you'd need to hide them behind hills, unlike the vanilla trucks that are limited by angle rather than range.

In our solo/duo game we did edit the mission to cut down the attack rate and aircraft count eventually, because it doesn't give you time to do anything except defend airfields. The balance is far more favourable when you have several players.