The Difference Between a Sprint and a Marathon
Literally every regular contributor to these forums has done single day drives of 700, 800, even 1000 miles on occasion, and the almost universal "been there, done that" response is "NEVER AGAIN".
It is one thing to drive 780 miles in a day when you are fresh and don't have to get up in the morning and get back in the saddle. It is quite another to try to do it at the end of a multi-day trip of many thousands of miles when you have already stretched your available down time to the max. I cannot emphasize enough what a terrible idea it is to try to drive nearly 800 miles at the end of such an exhausting RoadTrip. Simply put, your experience "[doing] the drive from Louisiana to Columbia a few times" in the past is meaningless in relation to your current plan. Do not attempt this.
AZBuck
