Stone Bell Strategy?

I seem to have trouble with this and some of the other "speed" type missions. I generally send a squad down the left and right flanks and try to take out the tanks and all those foot soldiers on the road with my third squad. I guess I am more of a silent sniper type player. I seem to just have to much to do at one time. I usually try to place the squads on my left and right flanks so they can defend a position until their area is clear. I take the third squad up the middle, If I go very far up the middle I seem to get my team killed about the time I get a shot at the second tank. I do best holding a position back up the hill beside the allies. From this position I can usually get both tanks, but before I can wipe out all the foot soldiers they get that front alllied guy.

I need a better strategy I think, but nothing I have tried seems to help. I can win ok on the easy level but when I get to normal or veteran I end up pushing up daiseys.