Thanks for the information, everyone.

For whomever asked, I'm 44. I also would like to try backpacking, it's not just my son who is interested. We have done zero backpacking, but we do fairly lengthy walks (5-10 miles) without equipment. We live in San Antonio, and my son's eventual goal is for us to backpack in Big Bend. Not sure how safe that location is, given its proximity to the border ...