the heroic level is easy but the trick is destroy all the enemy static arty before advance far in the map. This is due to you need to flank the enemy tanks in order to destroy them easy. In that case several of the 88s can be destroyed by landing paratroopers near and throwing grenades (be sure of destroying them, not only kill the crew, because other enemy infantry could take it again)
This is possible until you can reach the airstrike, then with the airstrike will be more easy destroy them
