First, I almost never have more than a few people behind me as I pull over when needed and can safely do so. Second, emergency flashers are just for that, when you could use some help, not just because you are stopping.
This is one of the reasons I'm asking, what is a reasonable speed that can be planned on. A 45 mph average requires running about 55 with only occasional stop for fuels and stops.
A 25 mph average may be running 50 mph with more stops that are longer.
I realize everything will change and I'm only looking for estimates. Average 25 vs 35 vs 45 will mean a big difference in driving times over 4,000 miles.