There are some dealers in Europe that offer functional air bags for the Tamiya and Wedico trucks. With compressors, load valves, and the whole nine yards. I can't find the website now, but I'm pretty sure it was a German hobby shop.
While you wouldn't be the first to have a working airbag suspension on a model truck, you could be one of the few I have ever seen, or known about.
I wish I could find the website, but all I can find is a movie on youtube.
http://www.youtube.com/watch?v=BY8Ly...eature=related