First of all you picked one of the most busiest days of the year. And one of the most
popular destinations in the park.
You need to get your butt to the permit station the day before you want to enter and get one of:
Glacier Pt to LYV
Happy Isles to LYV
Happy Isles to LYV Passthru (Sunrise)
Even getting there early on THAT weekend may not get you it... there may well be a long line already..
and only a few people can grab alot of the permits....
You can legally camp anywhere beyond the JMT/HD trail junction but not on Half Dome or the
dome preceeding HD. It will be obvious.
If you get GP to Illiouette then you have to camp in the Il. Basin on the first day.
Buy the NG Trails Illustrated Map of Yosemite. It is the one they have in the wilderness centers
and will show you where you cannot camp. If you abide by that map then you'll be fine.
(if you see a fire ring in that zone then some schmo who didn't know made one and either
they have given up and allowed people to camp there... or haven't come thru yet and removed
the fire ring) (don't make new ones... you're just creating work for rangers who have better things
to do)
My suggestion is to just go in there the day you want to backpack and ask for what you
want. When they don't have it... take whatever they got... it's all good...
Sorry if I didn't answer your question or said 20 things you already knew...