a number of friends in pro audio have cases like the following that they store in their trunks. a little heavy to haul out, but easy to move once out, things don't bounce, and the handles make it easier to put back in.
http://www.canyonwestcases.com/sources/ ... Cases.htmlI always got along with a milk crate with a plastic liner (cintra or something similar) that went up the sides a few inches and a briefcase style tool box or three as someone else was bringing the big bucket of gear (rigging tools case, dewalt driver, ele tools case, etc etc)