My first full size stunter was powered by a Fox .35, I didn't know how to set up for the 4-2 much less fly. I set the engine way too rich and it was a very windy day to compound the problem. Every time I hit the windward side it would fly across center and it would catch with a very hefty jerk on the other side of the circle. As a new pilot I was scared to death!!!
I filled the tank up with a full 4oz of fuel so you can imagine how much of a pain it was to repeat the scenario for countless laps.
I still fly that old Ringmaster and the Bellcrank is fine. I was using a "Hot Rock" with no thong and I was able to hold on. I can imagine with a very large stunter it would be very hard to hang on, but doable.
Not sure how you can mitigate the problem you are having although there are variables you can control before flight ie: engine run and wind conditions, line obstacles etc. You have been doing this much longer than myself so I am sure you know what to do.
Hopefully your wrist won't break, and I think worst case is you will be taken off your feet, or at least to your knees. That's very worst case...