In my trucking days 8-10 hours at a stretch was normal. Sometimes a bit longer. Erie, PA to South Portland, Wells, or Bangor, ME non-stop was a fairly regular thing. Since I was solo I could do whatever I wanted in the cab. 20 oz Mountain Dew, quart of truck stop coffee, loud music, me singing, etc (and once upon a time, little white pills - shhh). When traveling with family we used to travel straight through from Jamestown, NY to Booneville, MS. With family I couldn't do anything I wanted. Book on tape with ear phones. Stop in a rest area about half way for a 20-30 minute nap and the stop would wake up the rest of the family and they would begin stir around and start talking, which would keep me from sleeping. I would get aggravated enough that I would be fully awake in about 5 or 10 minutes so I would give up on sleeping and just get back on the road.

Travel with a dog so that you have to stop occasionally.

Best suggestion: drive it like you would drive a 318 Detroit and you'll stay awake ;-)