This is absolutely ridiculous and broken, I wouldn't try unless you're trying to 100% (99% with missed event achievs). Destroy all neutral buildings you come across. You can use ground fire to shoot through a destroyed building when enemies can't see you or fire back. Eventually they will try to move in on you, but with your free flares you can see when this happens. Try to circle the buildings and keep out of LoS of tanks as much as possible. Ideally you should make it to the final phase (Destroy 8 tanks) without taking any or much damage, saving your resources for Blitz mode if you do get caught by the KV heavies. Save literally after every encounter you come out of with 0 damage, even if you only got 1 shot off. I spent probably 20+ hours save scumming the last phase to beat it, with one shot of health left.