I drove 12 hours via Hume Hwy Syd to Melb i got back ache for a day in Melb, but that's because i slept on my side on the driver seat for 1 hour during the trip!

Then on return, I drove 14 hours from Melb to Sydney and just had some tiredness and the next day i was back at doing gardening / mowing the lawn and doing all the usual weekend chores.

Try doing this on a DC5R Recaro seat and you'll appreciate the CU2 seat