Yeah, I'm pretty sure that the permits are only required for camping within the wilderness area which doesn't start until the very top of Buchanan. You probably also need a permit for one of the designated spots at the bottom at Camp Dick. I do know from a backpack trip a couple years ago that you need a backpack/camp permit to drop down within the actual wilderness area - like on the trails up to Audabon, Sawtooth, etc. No bikes in wilderness either obviously.
I did stay at GGSP last night. $5 fee to get in and then $12 for a tent spot. Very nice though and they have shower facilities down the way which is nice post-ride, pre-sleeping bag. The pre-camp ride though ended in tears as I somehow managed to rip my pedal right out of my brandnew XT crank arm. That was a first. My guess is that I slammed it hard on a rock (180mm arms) which bent the axle within the arm threads and then just ripped the threads up when torqueing back up on the climb. Noticed the problem, tried to snug it, but within another mile the pedal ripped completely out of the arm. Then it was miles of either one-legged pedaling or pushing back to the campgrounds. In the rain. Less than ideal. Rant over. S