Didn't you have a similar accident some time ago? (or maybe someone else) I think the best way is to prevent the same thing from happening again, if you put your plants on the ledge, then find a way to prevent them from falling. Some kind of rail?
Please be careful because the other way might also happen, if your plant falls and hits a vehicle then that vehicle gets damaged or gets in more accident, you might get in trouble too. So it goes both ways.
For your Truncata, yeah unfortunately the best way is to just put in Intensive Care, buy repotting, then bagging. hopefully it will survive. If it does, call it Super T!
TTFN
Arvin