GEVs are great raiders, but they're not suited for the kind of stand-up fights that occur in Ceasefire Collapse . Don't choose many GEVs. A GEV raider coming up and retreating along the east-west road is another possibility. GEVs are the best units for mixing in on the duel of Ogres that usually precedes the armor battle, and living to tell about it. IF you do take a lot of GEVs, try to keep them together.
Infantry is good for delaying GEVs, especially in a town or forest.
I mentioned above the possibility of exposing CPs to distract enemy GEVs. MSLs are good things to have backing up your HVYs in a battle, but their low speed and sensitivity to terrain make it difficult to get them there in time. Choose one or two, maybe, intending to keep them on the road to offset their speed disadvantage. Try to keep them four hexes away from their targets, with a line of HVYs or infantry in between. The basic job of a MSL is to shoot at enemy units from outside their range, since MSLs don't last long when shot at.