As much as i was looking forward to a night assault, I agree.Go with the dice. I think the AC determination gets a -1 mod for the next campaign scenario. That should turn up the heat.
I think rolling for escape was the right move:
12.6073 ESCAPE FROM ISOLATION: Each Isolated Activated ENEMY unit/S? must take a NTC; there is a cumulative 2 DRM that applies if in a VPO Location. Any ENEMY unit that fails the Task Check must attempt to Escape. Each Isolated S? must take the NTC using a mo-rale of 7; if it fails the NTC it must check for Activation and attempt escape (as a stack if other units stacked with it are attempting Escape).