I did my Iron Butt ride several years ago, starting about 1 minute after my 70th birthday. I decided to ride it at night as the GoldWing has wonderful lights, temperature was not that bad on Feb 25th down here and much less traffic at night. Also I wanted to be sure that I never rode looking into the sun. We dressed warm and both of us were on Wings and it had good coverage against the wind.
So we left Valdosta, GA and rode I-75 south until we hit I-10 to Jacksonville, FL, then we turned North on I-95 and rode through some really heavy fog for a couple of hours. Stayed on I-95 out to a little west of Florence, SC where we hit I-20 west. After an hour or so going west on I-20 the sun was coming up on our backs and we highballed it through Atlanta where we took I-85 south west and rode that through the mid-afternoon on to Montgomery, AL. There we got off the interstates and took Hwy 231 into Dothan, AL where we loaded up on several dozen raw oysters at Hunts Oyster Bar. Then on to Hwy 84 which is mostly 4 lane, back into Georgia and to Valdosta, arriving there at about 6:30 pm and the Garmin GPS said we'd done 1,162 miles in 18½ hours.
I felt really good and thought, like lots I imagine, that I'd sleep for a few hours and then hit the road and get in the other 400 miles to make it a 1,500. But when my butt hit the sack I was gone for a day. But we had fun and it was nice to say I did the 1,162 on my birthday.
Note - my best friend is a doctor. Have ridden with him for thousands of miles. He says that a Tylenol and an Excedrin taken together will give you about the same boost as one of those 'energy' drinks. I chose the two pills. Boosted me up and took care of the pain from my degenerative disk in the back. The Utopia back rest helped loads too. Take two pair of sun glasses as you might leave one up on top of a gas pump
Snicker bars quench the hunger and boost you also. Drink plenty of water. Pee at each stop, especially in winter time. A full bladder makes you colder. Remember to get a receipt at every stop and at every road change as that has the date and time on it.