Last year I created a track just for fun, to see if I can do it. I was positively surprised about the result. It's not perfectly fancy-looking, but it was fun to drive, so I wanted to publish it

Best case scenario would be if the user falls down, they hit an invisible object and instead of crashing they are rescued. No matter which configuration for this object I chose, the kart mostly just lands on the element and continues to drive on it, without being reset/rescued. Strangely, the kart is only reset if I collide with an edge of the object.
I also tried combining the above settings with other settings like "Ignore (ghost material)" but that did not improve anything. I tried to use extruded objects, instead of just planes, I varied setting the type to Object and to None. I have no idea what else I could try...
Can anybody give me a hint which configuration would be used to rescue a car automatically if it falls down somewhere, so I can finally publish it? If it helps, I could post my .blend file here.
Thanks very much in advance!