We did the restroom stall stage, but had the shooters legs wrapped with a bungee cord, to simulate the dropped pants.
We used to have a 6'x4' platform that was suspended, by wires, from a surrounding frame. Bungee cords helped limit/damp the movement. We used it as a boat, and as a window washing platform, at various matches.
We've done a couple of "bad guys come knocking" stages, with either "frosted glass" (translucent plastic sheet) or a peephole in or flanking the door. In the former, you get a distorted view of the targets' locations, and with the latter, you have only your mind's eye memory of where the targets were as you engage them through the door.
Shooting fram a moving vehicle is always fun.
A stationary vehicle is a great prop, too. I wanted to look for a mini pickup cab, to mount on a dolly that could be easily rolled around the range, but without having to park a complete vehicle at the range.