I think front air is possible. Kelderman makes a front air system for the 4WD, the problem with the 2WD that I have is two fold: There is less room for the bags so you need high pressure (smaller diameter) bags, and the twin I beam mounts the springs or bags inboard with some leverage, so more bag capacity is needed even than the rear. Some guy built his own on the truck forum, and he said it worked very well until the truck got stolen!
The bags for my rear system are around $150 - less via internet discounters.