You might want to try one of the snowboard boot dryers. They work great for their designed purpose and I imagine would work on booties as well. Also, like others have said turn them inside out. However, you don't have to turn em all the way inside out. Just turn down the sock part of the boot, and then place booties on the passenger seat floor mat and ride around with the floor heat on max. This will do the trick, especially if you have to drive to the beach a little ways. Toasty boots by the time you get to the surf spot.