What is the nature of the your cellphone coverage in that area? That would a key factor. I imagine you are planning to do these trips fairly soon. By May the Supes get pretty toasty.

The storm predicted for this coming weekend should wet things down fairly well.

Your gear list looks pretty good. What is ten feet of rope for?

I don't believe you mentioned a signal mirror. Take about five minutes and learn to use it. Well worth it, especially in the American Southwest.