Gary...there is only one way to do this trip and remain in good shape. Drive for maybe 1.5 hrs and then stop...take a walk around. Maybe for 15 or 20 minutes? Then repeat. You can get 6 hrs in a day of you follow this regimen and you'll get to Alaska and back with a smile on your face. If you rely on cushions and so on, you'll end up in a world of hurt. I have 37 years behind the wheel of a city bus and back injuries to boot. The Opus is great..for a day, maybe 3...but you are talking a long long drive. Maybe 10,000 miles. You should set aside maybe 4 or 5 months...and have the trip of your life.
And...take a day off whenever you want to. Just kick back...do what you like to do.
Just recalled...you can buy and have installed a proper drivers seat. Recarro. You'd need an on board air compressor...like the ones for air bags? Same same.
Gary Haupt