These people rent gear specifically designed for Whitney trips (among others). While located in Scottsdale AZ, they ship to you. They have mattress pads. I have not used them so this is not a personal recommendation, but I thought that their website and approach were pretty good. (However, the pad they are listing, at 1.6 pounds, may be a bit heavy.)

Mt. Whitney Gear
http://www.lowergear.com/product.php?cat=44

Mattress Pads
http://www.lowergear.com/product.php?cat=48

Last edited by Akichow; 06/28/10 06:34 PM.