PHX had a private bathroom / shower. in a terminal. Make friends with the 24 hour food vendors. Remember there are dozens of legit people sleeping that missed there flight or whatever so find you a dark corner.
Good luck.. here is a cyber smoke and some change .. Gotta ask. Why you homeless? ? 
So, why you homeless? Drugs, booze or are you fucking crazy?
In fact, I'm wishing I bought a Mercedes Customized Sprinter Van for the same amount my Camry cost. Those things have a fucking "million mile club", and even 550/month is better than rent in some places.
You could then go habitate in that van in a location, lower in elevation, alongside naturally flowing running water.
I once lived at rest areas and national parks for 6 month 15 days. And It could happen again, especially considering my level of negligence.
I'm not homeless now, and your introduction is eight words. I hope that you can walk to a library and use a computer there. I'm at a public library now, and anyone can get a guest pass to easily use a computer for free. There's a time limit for three hours for every guest pass. You can easily get a second guest pass after your first session ends in three hours.