A fleece blanket should be warm enough, with a closed cell foam pad from Wal-Mart or an outdoor supplier to sleep on. Sawyer mini-filters (Google them) will give you water from the river and only cost 25 bucks. Cookie tins, like those that have snow scenes and Santa on them will keep the critters out. They've worked for me in the canyon farther east. I glued some Velcro to the sides and lid to keep them shut. They work against the squirrels , mice , ringtails, and ravens. One should be enough for an overnight. For just one night you can consider bagging cooking and not using a stove. Your friend who backpacks should be familiar with cook/no cook scenarios. You can easily live on some crackers, nuts, granola, jerky etc.... and even drink some cold instant coffee if you need caffeine. Prof. gave you great advice about the heat, and I would suggest Gatorade or something with electrolytes for the hike. You should be able to fir everything into a pack around 50-60 liters. All over the place in price range from 60 to 360, so it depends on your budget. For cheap, maybe look at the Kelty lines. http://www.backcountry.com/kelty-redwing...0NhdDcxMDAwMDc1
There's an example. Not the cheapest, but decent and useable. If you can find them in a store, try them on and get it fit to you. You'll be glad you did. The falls are on my "someday" list. Right now, I'm still doing much more adventurous hikes in the NP. Won't be too long before the knees won't take it anymore, though. Have a blast and take some pictures to show here, Please?