There is a Walmart parking garage here, typically with around ten overnight parkers. There are signs saying not to park, but it's not monitored, and people park there overnight all the time without ever being bothered. It's not clean, but it's sheltered from the wind, rain and snow, and it stays really cool during the day. The Walmart is really near, so you can use the bathrooms and wifi there during business hours (they close at 11 pm.)