With all this talk about gas shortages and whatnot.. I would use a car, yes, a big old Mercedes or Volvo diesel (or my own 65 Dodge Dart if I can retrofit it in time) that could run off grease and/or biodiesel. Self-replenishing fuel supply anyone? And if I had my Dart, well, that's all steel around me, none of this newfangled plastic that breaks so easily.
I would go with walking if it's short distances. But you could wear leather, sweaters, hard hats. Pretty much anything that could slow down/soften the bites. Hell, if you had too, you could even use duct tape but your skin wont be able to breath at all that way so make sure it's a very short distance.
As far as long trips a 15 passanger van is a thing to contemplate. The engines in those things are great, they could easily run over big "objects" plus they have room for weapons and supplies.
Reguardless of the vehicle I think you should make sure you have a great driver who is good under pressure and knows the area/good at directions in your group.
You know I never thought about using ducktape. You don't have to put it on your skin, you can put it on your clothes. Make a barrier, something to stop the bites from getting through. Be bitch to move in, but that is an idea.