I get where you're coming from. It will work for random encounters (you can call common event) and event encounters, but it won't work if you die from poisoning, while you are still on the map? I can't think of a way around it, but maybe you could give the player antidotes and such.
Maybe even a warning. And a question, if they did get the option to start or give up, if they chose start, where would they end up? Their last save point or just before they died?