It might fit into the frame of a Wasp but from experience of marshalling on classic trials, I'll never own one, simply because if ever there was an off road vehicle designed to maim or kill its occupants, a motorbike and sidecar definitely fits the bill!
On a steep unsurfaced hill, the sidecar wheel is bound to hit its share of rocks, or drop into holes. This tends to pull the outfit to that side (to the left on a UK outfit). To get over the rock, or out of the dip, the rider has to apply more power, whereupon the rear driven wheel pushes the outfit even further to the left. The outfit might already be needing a lot of right lock to stay straight on the hill.
This sends the outfit towards the bank on the left side, possibly against full right lock. The sidecar wheel then runs up the bank and the outfit flips over to the right. I've helped pick up a lot of competitors who have fallen foul of this dirty trick; not unusual for them to suffer broken wrists/arms/shoulders as they try to fend off the ground and have the sidecar land on them from above!
Here's one doing it on the flat!
https://www.youtube.com/watch?v=LNwVmIUmwBIBuilt like a gun... could go BANG!
