There are two spots that are invincible from the tank.

1. Blood Harvest finale. When you get to the house, there should be a barn nearby (it should be near where the truck comes to pick you up). Once you are in the barn, climb the ladder, and if you turn around you should see beams. Walk to the end of them.

2. Death Toll finale. When you get to the boathouse, go to where the boat picks you up. You should see some rocks. Walk over to the rock next to the wall. Jumping onto the rock is kind of hard, but you should be able to get up there.