About a year ago, Kyle Smith posted an article in Hagerty's magazine that was pretty thoughtful about deciding what tools to pack in your car to save you (and others) from a dilemma on the side of the road. This dovetails nicely with my annual early spring look at all my on-the-road tools and spare parts to replace those needing replacing, dropping things I'll never use (like my old 009 distributor parts to be replaced by Magna-Spark versions) and adding new things that look promising, like a large HD trash bag that can have many uses (Thanks, Jack Crosby)!
I no longer carry enough stuff to do an engine rebuild (don't laugh) and I've become more realistic about what could actually get done on the side of the road and have been adding things that I think are more useful to me and others. Kyle's hip flask particularly caught my eye - That'll be added, for sure, but I won't be putting 2-stroke oil in it. 
You never know when it's gonna be a long wait.
So here's the Hagerty article from a year ago, with hopes that it will help others to decide on what they need to bring, based on their individual mechanical ability beyond their insurance company's roadside assistance number:
https://www.hagerty.com/media/...ng-a-custom-toolkit/
This was followed this year by another road tools article from Brandan Gillogy, although their OBD tool might only be of interest to the Suby guys: