Been there, done that..I changed out a dead alternator on an old Ford LTD I had back in the 80's. I did that one on the side of I-75 in the freezing drizzling rain in Atlanta, Georgia. I beleive it was Christmas Eve to boot.
Another year I was in the Georgia mountains not too far from Ellijay, Georgia and the water pump quit on an old Toyota Celica I was driving at the time. This also happened at Christmas time and pretty late at night too. I coasted it downhill to a country store in the middle of nowhere and my buddy Travis and I went back on Dec. 26th and swapped out the water pump and replaced the shredded drive belt in the store's parking lot. I was flat broke at the time, and Travis paid for all the parts I needed. He also bought me lunch that day too. Travis was and still is a very good friend.
Another time I was up in North Georgia near Gainesville, also at night but not at Christmas time, I was driving my old 1978 Audi Fox and the headlights went completely dead, it was pitch black dark, out in the country. I pulled off on the side of the road and found that the high beams worked (all four headlamps on at once) so I just disconnected the two high beam headlights and left the multifunction switch on high beams and went on home. I never did fix it properly, and I drove it like that till the day I traded it in.
I have done a few battery exchanges, light bulb replacements and once I R&R'd a bad heater hose on a friend's Honda Civic, all in the parking lot at an auto parts store. I saw a minivan ahead of me one time blow out a tire and come to a screeching halt on the side of the road once here in Florida. It was a two lane road, in kind of a rural area. I stopped to help, it was a woman who had no clue how to change the flat tire. I changed it for her but it did no good, the transmission had locked up which was what caused the blowout. I remember it was mighty hot on the side of the road that day.
I must say that I haven't done any side of the road repairs that are near as dramatic as some of what you guys have posted here. I do carry a pretty good tool kit and some good flashlights and rain poncho's in case I wind up on the side of the road again. I sure hope I never need any of the emergency tools I carry around with me.