Nah, I tried it about 70-80 times the other day, against two parked right in the hanger.
I discovered that the T-34 does indeed traverse faster after being shot about 50 times in a Panzer. Still not fast enough though. My strategy was actually to run them out of shells and then whack them, unfortunately, the base was capped before that happened.
So take the back door away. Make it abit more of a shootout, or force them to try to destroy the VH, rather than camp it, it will do the game good.