321BAR, good defense relys on absorbing the enemy's attacks in multiple supporting possitions. If I were to be put in command of 6 tanks (Panzer IV's even, which aren't much when put against a koinstiger, or an elephant), I would be able to make a formidable defensive line.
Personally, I believe in using blitzkrieg tactics for defense, and Kursk style tactics for defense. Sure the knits can take any one possition, but how many untill they get tired of loosing perks by the hundreds each spawn?
As I said: to make it work, we would need something free (or at least cheap) thats armed with the KwK43. I proposed the Nashorn because its weak armor makes if very vulnerable. Il-2's will be able to kill them from the FRONT. Any vehicle mounted cannon firing AP will tear right through the armor.
You have Jagdpanthers, Koinstigers, Nashorns, and other Elephants to deal with the attackers from the front (elephant will likely be added last, IMO). Also, (in an ideal situation), you have jagdpanzer L70's, Panthers, Fireflys, T-34/85's, and Tiger I's that will be able to penertate the side armor at a good range. It would be vulnerable to the Panzer's and M4A3(76)'s gun from the side at med range as well.