Does it have to be air? Maybe go with a simple hydraulic setup. If all you are wanting to do is drop the van when you park. Or for a little bit more you could go with a 2 pump setup..SHOWTIME HYDRAULICS offers this kit for 999.00
ShowTime Chrome
Two ShowTime Chrome pumps (pictured here) or four ShowTime Chrome pumps, fittings, standard check valves, competition dumps, #6 high-pressure hoses, 8" street cylinders, slow downs, cups, donuts, street switches, solenoids, switchplate and switch cord.
or from COOLCARS you could get this kit for 899.95
STREET EDITION
You have many choices on what to do.....