If you can do it, there's a Boy Scout camp next to Pendleton that might be useful. I know there are showers there (I installed them for an Order of the Arrow project back in the 90's), but it's not a full-on camp so there aren't weapons and food like there would be at a regular camp.

I'm not sure it's safe for me to head out of Fullerton, but I don't think I'm going to have much of a choice here soon. I'm thinking if I move along the train tracks I'll at least have a decent line of sight.