AT guns HAVE an important offensive role in the isolation of a battlefield segment, and that role helps them survive! First, figure out where those nasty defensive German armored vehicles probably are, and what section of the battlefield you want to isolate, so you can move through, assault or control an area.
Place AT guns in a hide position with a carefully LIMITED field of fire along an axis that separates your chosen avenue of approach from the other places where the enemy probably has his forces (maybe along a road, or other somewhat narrow open strip, hillside, etc.) Then, when your approach is detected, and the enemy moves his pesky armored vehicles (especially those Panthers and Tigers) to defend the sector of the battlefield you are threatening, Bam!! You light them up as they cross your AT Gun's narrow field of fire. Often, you will get a side shot, important for Kitty training with our (U.S.) guns that cannot usually take them out head-on.
Since the field of fire (and hence, exposure to the view of other enemy firepower) is narrow, there is a good chance your gun lives to brighten the day for other armored vehicles.
The main result of this is that the enemy is severly limited in his ability to relocate his defensive forces to the part of the battlefield you have selected to overwhelm. Your initial 3-1 advantage is now 5-1 to 10-1 where it counts. I don't smoke cigarettes, but I LOVE to smoke Panthers and Tigers.
Thus, one working approact to the use of AT guns on the offensive limits enemy mobility and his ability to react to your attack, it protects the AT guns, increases their effectiveness verses tanks they cannot engage frontally, etc., etc...