[@Section] I for one think the tank idea is cool. If you pick a large enough tank, you can make it a shelter too.

Better idea: use an APC (armored personnel carrier). The bay area is big enough for a Jeep, so you have plenty of room for a weatherproof and bulletproof sleeping and supply zone. It also has a turret gun and needs a crapload of fuel, and it would be fantastic for character development because people could start to develop claustrophobia, or you could find supplies that are too valuable to leave, but are so bulky that someone has to sleep outside.