Here are some pictures of the ones that we used to use. Could not find the bus (must have gone back to storage) but I did get these:
You can see some of the camera stuff we mounted in the cab of it:
And a rear shot. This is the same style trailer I have at home:
Wish we still have the working one of these systems in house, but unfortunately it was scrapped when we moved buildings. I'll see if I can find some old promo material on it though. I know we have one ot two systems still out there.