Side of the Road Repairs

[kk2002s]

In modern cars, it's getting harder and harder to band-aid your ailing car back home or even off a highway.
What repairs can be practically done on the boxster to get it going again or at least limp it somewhere?
What tools would you need?
I can see carrying a spare belt and socket/wrench
I can see carrying a gallon of distilled water
Fuses, relays

Are there other repairs that could be fixed, if not permanently, at least temporarily so you can get to where you needed

When ever I travel some distance, 100+ miles, I bring tools, my old serpentine belt, spare fuel relay and a light but I don't know if there is really anything much I could do besides those simple things.