[lincpimp]

Ok, I have a few ideas.

First the body will have to be made differently to cover the electonics but leave a portion of the chassis exposed. The lipo would have a hard case, with some sort of female bullet connectors, most likely at each end. A small base, attached to the chassis would have male bullet connectors pointing upward. Use 4 steel round posts on the base, one at each corner that will go thru a corresponding hole in the hard case. That would keep the pack in place front-to-back and side-to-side. A special over center style latch would hold the pack to the chassis and when unlatched would lift the pack off the chassis to aid in quick removal.

I have the latch mentally designed. The molded hardcase would require a bit of design, but could be a 2 piece item that just bolts together. Maybe some foam inside for impact assistance? With careful use of materials weight could be kept down, maybe not as light as a conventional tray though...