I do have the stock seat... but added a taller shield, and hand wings... passenger floorboards and backrest riser. And now my GF gets so comfortable on the back that she d*mn near falls asleep! How's that for an endorsement?
When she's happy, I'm happy.

So now it's like Stroguy said "...three hours of driving and then a fuel stop, walk around, drink, eat, repeat."