Pioneers crossing the country in Wagon train day's didn't do it at 70/80mph. Years ago I did a lot of motorcycle cross country travel. The hottest was arriving in Laughlin Nevada at 3pm when the temp was 119 degrees. I was cooked and done for the day. That was a 2 week tour that included a lot of hot spots enroute to the Dakota's. The trip back to Ca. was not bad at all. I used the safety precautions. The water saturated neckerchief, long sleeved cotton water soaked shirts, under the gear (last about an hour) hand held spray bottles, etc. Most importantly is to keep yourself hydrated. That seemed to require a lot of stops and just quit when you get tired.