Replying to Camping on the Mountain

Thinking about planning a trip out west early this summer to try and catch some of the snow that they've been getting. I love camping and definitely cant afford to stay in a hotel. Does anyone have any advice for that kind of a setup? I assume there are probably camp areas nearby but are they close enough that I could walk to and from the mountain? I also read that article on the tent city near Mt. Hood. Areas ive been considering are Squaw, Mammoth and Mt. Hood but I will take any suggestions as to where people might be less inclined to arrest me if they see that ive been living on their property. I generally pack pretty lightweight, sleeping in a hammock with a tarp or bivy sack. Should I bring a 0 degree bag or will i be fine with an old 20? I think i'll be there for about a week and all advice is appreciated.