I was a Ranger out at Philmont in 1996 and now get to go back each summer for a week through the Philmont Staff Association. My son is only 8 (cub scouts), so I have a few more years until I get to go with him. I did do a full 12-day Philmont trek back in 2014 with my old council in Illinois, as they needed another adult, but primarily I have been doing the week treks each summer with other former staff.
As you already know, the lighter your pack, the easier (and better) time you are going to have. Plus, it is easier on your back and knees, which I have found to be VERY important the older I get. That said, Philmont does present a unique challenge as you can’t really go “true” ultralight. Philmont has thousands of people a year go through their doors and out into one of the most amazing pieces of property in the world. Philmont has to make sure it is done safely and minimizes, or at least focuses, the impact. This is why they have very specific rules in regards to things like no hammocks, how you cook and store your food, etc.
I am also a huge fan of Zpacks and use a Zpacks Triplex, 20 degree bag, poncho/groundcloth, dry bags, warm hat, gloves, etc. on my trips to Philmont. Sometimes I feel like a walking advertisement for Zpacks. I personally picked the Triplex because it is still light enough for me to carry by myself, but big enough to comfortably sleep two grown adults without having to touch. This is helpful as I don’t always know who my tent-mate is going to be until the very last minute.
In regards to the pack, I personally would avoid getting a Zpacks pack. I like them. They are great. However, they don’t do so well when you get to the upper limits of their weight capacity. I tried many different packs until I settled on the Six Moon Designs Fusion 65:
https://www.sixmoondesigns.com/collections/backpacks/products/fusion-65
It weighs 52 ounces, so it is heavier than the Zpacks, but it carries weight really well. I have used this pack on my last two Philmont treks and will be using it again this summer.
Prior to my purchase of the Six Moon Designs Fusion 65, I was seriously considering getting a Zpacks Arc Zip for my Philmont trek. If you look on the webpage linked above, you will actually see my review which compares the two. I’ll also post it here:
“I have now had the chance to take this pack on a couple of prep hikes and I have been very happy with it. I have the pack right at 40 pounds for my prep hikes. This is probably about 5 pounds more than my max weight will ever be during my trek, but I want to prep for worst case scenario. This pack is very comfortable, even when carrying 40 pounds. The updates for 2015 (overall capacity, color options, larger side pockets, etc.) are all great. They addressed all the issues I had with the original version. When empty, the pack weighs exactly 51 oz. (standard yoke/medium belt/hydration pocket). While this is not an ultralight pack, it is one of the few that are this light and can still carry a heavy load. The ZPacks Arc Zip (27 ounces configured how I would want it) and Gossamer Mariposa 60 (36 ounces) are both lighter. Both of those are great packs, but they really drop off in comfort when you get above 25 pounds. For what I am doing, a max weight of 25 pounds is just not feasible. The Arc Zip is also much more expensive ($455 configured the way I would want it). Overall, I am very happy with the 2015 Fusion 65. It is a comfortable, lightweight pack that can handle a heavier load with no problems.”
That review was done in April 2016, before I had actually done my Philmont hikes with it in the summer of 2016 and again in the summer of 2017. Once I did those, I was even more pleased that I had picked the Six Moon Designs over the Zpacks.
My base weight (no food, water, or crew gear) for Philmont is 19 pounds. Not true ultralight, but still pretty light for what Philmont makes you take.
I have a full spreadsheet that details out every item I carry and the weight. I am happy to share that with you if you like. You can use it as a guide. Just let me know.
One other thing that I would mention is: MAKE SURE YOU HAVE GOOD RAINGEAR!!!!!!
Can’t stress that enough. It does depend on the time of year you go (rainy season starts in late July to early August) and where your trek takes you (more rain in north country and less rain in south country), but having a good set of raingear is sooooooo important. Maybe you won’t need it at all (if you are lucky), but when you do need it, you will be glad you have a good set. You being dry will allow you to assist those scouts that didn’t plan as well (this will happen).
Congrats on getting to head out to Philmont in 2019. It is one of the most amazing places to get to go and I always love spending time out there each summer. :)
Let me know if you want a copy of that gear spreadsheet.