Don't let terrain be scarce. If you think there isn't enough, tell your opponent that you want to add more; the BGB suggests ~25%. If you don't have enough, make more!
Also, all your vehicles should never get destroyed in a single turn. If you've deployed intelligently, even in the absence of terrain, the wrecks of the first couple Rhinos/Immos to go should block LoS to the others.
(Edited for typo.)