Selectable lockers are the way to go. Normal road manners, but offroad...well...it's a locker

. ARB makes a great one, and contrary to popular belief you don't need a compressor to operate it, just an air source...a powertank would be great. A 20oz CO2 bottle would be good for approximatley 70 activations, then it will cost you $3 to fill the bottle, all without the problems associated with finding a place to install a compressor and then lugging it around. A 20oz bottle is about the size of a large bottle of shampoo-not much space taken up there...You could pick one up on eBay or craigslist or a flea market/garage sale or paintball store for anywhere between $15 and $50 (they're pretty much all the same...don't worry about price), then the mounting will run you about $100 new from Powertank, then you just have the cost of the locker itself. I HIGHLY reccomend selectable lockers over permalockers.