Which tactic can I use to pass the toxin stage with GLA forces which don't have aircraft bombing in hard level?

In Command and Conquer Generals Shockwave, I can't pass the stage which is full of toxins (usually stage 2) when I use 2 of the GLA forces which don't have aircraft bombing, in hard level. One of the other 2 GLA forces is the owner of that stage so I don't have to pass it, and the other IIRC has an aicraft bombing.

My tactic to pass the toxin stage when I use any of the 4 chinese forces is to put mines in the bridge, that way GLA forces can't pass through and I avoid their long range missiles. When I choose any of the 4 US forces, what I do is to use aircraft bombing to destroy the building that creates those trucks which have the toxin long range missiles, which are the main problem of the stage and pretty much destroy any defense you have.

But when using 2 of the GLA forces I don't have any of this. Even if I manage to create 2 scud launchers, by the time they are ready to be fired I have to use them to defend myself, because I'm being constantly attacked by their trucks with toxin long range missiles, and 2 other problematic vehicles they have. I've tried sending motorbikes to destroy some of their oil drillings to see if I can slow them down by making them having less money, to see if in the meanwhile I can create more scud launchers, but it isnt working. Also I tried to fill the defenses with those buildings which rebuild themselves, they are good to buy time but not good enough.

Any suggestions?