I do like the idea of making them cost a bit more. Not ridiculous amounts, but more than they're charging. My Dad and I were just talking about that today.
The time window, I'm not so sure about. Things beyond hikers control get in the way sometimes, especially on Half Dome. T-storms would be a big number one. But then again, that very thing might be a deterrent for some hikers, and that might not be all bad either.
I really think the non-transferable thing should be the first change.
