Awesome day hike. I learned that you can either reserve your own permit 2 weeks in advance or go on short notice with a guide. My lodge (Chiang Dao Nest - which I highly recommend) was able to arrange it for me the afternoon before. As an experienced climber and hiker, I was chuckling to have one guide in front of me and one behind the entire way - like I was a baby elephant. :-) It's a tough hike - 11 miles 3500ft gain, but nothing you can't handle if you are a regular hiker. So ignore the locals protestations that it is too difficult and dangerous to do in one day as I think the Thai, while active, are not super adventurous people. It was also surprisingly cold on top for me and clouds obstructed my views, but I said "mai pen lai" as the Thai do ("whatever may be"). :-)
Superb dayhike and loved the views of the surrounding peaks and cliffs. Pretty cold on top, the only downside is the views were a bit tarnished by smoke from the surrounding areas. But would love to go back sometime.
"After the first glass, you see things as you wish they were. After the second, you see things as they are not. Finally, you see things as they really are, which is the most horrible thing in the world."
--Oscar Wilde on Absinthe