Went on our maiden voyage last Thursday (returning last night). 700 miles round trip through many mountain passes.
Truck with 18K SuperGlide handled perfectly. I'm very glad we added the air bags to my truck though, as it really smoothed out the ride.
On a sad note however - somewhere upon our return home, the spare tire on the 5'er came off, apparently hit the right rear leveling jack, knocking it loose. It must have dragged behind us, because by the time we got home, not only was the spare missing, but the leveling jack was essentially destroyed.