Intersting choice of parks, no potable water there, and its desert camping, no river, but it does have horseback riding.
Personally I would find a park with trees and a river but all parks can be fun.
Kids can help with meals like foil packs, or hot dogs, then do your own star gazing party at night.
Be excited
If you aren't excited about an adventure, you can't expect a child to be. Point out everything as if it is the first time you have ever seen it. Show how to do something, whether it is gathering sticks for a campfire, or cooking or tying a knot. A good idea is to bring extra plastic garbage bags to pick up any trash you come across. Kids remember when they do something right that somebody else has done wrong. TAKE PICTURES OF YOUR CHILD HAVING FUN, they sometimes forget until you bring them out. Did I say to have fun.
