All my above advice is based on real life events. Numerous PhilSARs have occurred from some of those things. Completely agree with CCard that you have to find what works for you. Try things out. I have a closet full of things that I tried once and decided I didn't like.
Chacos, for some reason half the rangers like to wear them backpacking, but BSA rules do mandate closed toes, so chacos with socks is the solution. Shoes though, that's critical. You have to do what is comfortable for you, don't skimp. Ankle support, you'll see people go both ways. I've found the older I get, the more I need it. If I am doing day hiking, sure, my trail runners are fine. But when I put weight on or hit the mountains, I prefer that ankle support.
Padding, buddy of mine legit did that with one crew. Just took his foamie, rolled it up and strapped it to the outside of his pack. Quite a sight to see going down the trail. But when you are out for just two nights, you can do fun things. I haven't found a sleeping system I like yet, except my cot which doesn't help on the trail. I've tried some inflatables , tried z-rest, tried combining, and just haven't been pleased yet. Interested to see what CCard is using.
Sleeping bag, I haven't had issues with. My main concern is just size in the bag. Summer at Philmont, by the time the crews are there, unless you are in the Baldy Country, typically upper 30s, low 40s. I would use a 2 season bag and be fine. I later started using just a blanket. Interested in the quilt, CCard. Is it just a flat piece and you roll up in it?
I truly do want to punch people in the face who use bluetooth on the trail. I typically avoid the more social trails, but even mountain bikers are doing it. But using phones for guidance, people try it at Philmont. Did one SAR where a group of 4 boys went shwacking by themselves with a GPS. This was before we had these fancy smart phones, so it was the big GPS units. They didn't upload maps to it, so it was pretty useless. They didn't make it to camp that night and slept with no gear. No worse for wear, but the advisors took the brunt of it from Leadership. Learn the map and compass, don't trust the trail sign, and regular crews should not be shwacking.
Food, you'll lose weight. But don't worry, you'll gain it back afterwards. I was going lactose free when I worked there, so I typically brought my own food on the trail, but when you are hungry, anything tastes good. I don't remember complaints about the food on the trail. Camper dining hall though, ate there last summer one meal. It was atrocious. Take the boys to eat in town after their hike. Even the Cree Mee is better than Camper Dining Hall.
Elevation, you max out at 12,4, so it is super high, but a lot of people feel it, especially when you are hitting 10+. Mark Anderson used to be big on trying to get someone to do research on the effects of elevation at these more moderate elevations, but don't know if anyone has. Drink lots of water, that seems major key. And start hydrating early. They will take your blood pressure at medical. I keep ibuprofen for the headaches. A buddy of mine would take canned oxygen with him and take a few hits from it. That seems overkill. I think lots of water is great and if you can get to elevation for a shake down, that's good. Maybe beet juice? The doctors at the clinic are from Kansas.
Weather-wise, I never needed more than a fleece. This is me up on Little Costilla in July 2004.
Even earlier that summer when we did training up at Copper Park and there was still snow, my fleece was sufficient.
Later that summer I was doing the marathon and hit rain at Shaefers. I only put on a rain jacket, no pants, and that was a huge mistake. All that water caused real bad chaffing. Lesson, don't pick your clothes based on trying to be cool. Don't skimp on staying dry.
Enjoy the hike!
Why even take a cell phone to navigate? I used to always say "you're not lost if you don't care where you are" and "all trails lead to somewhere." You can see some pretty cool spots on the ranch when you combine those two. "we're not night hiking, we're just late arriving" may also come in handy.