This is an old forum and my advice might be too little too late, but I stumbled across this randomly browsing the web and thought I'd weigh in.
Like Nick, I am a veteran of the Ranger Department (5 years total as a Ranger, Rayado Ranger, Ranger Trainer and Mountain Trek Coordinator), in fact, Nick and I worked together (Hey Nick!)
I see you mentioned that you hope to bring a lot of your own crew gear. There is a delicate balance to the art of bringing your own crew gear to Philmont, and most crews get it wrong and make things difficult for themselves. Countless times as a Ranger I had to tell disappointed crews that the expensive gear they brought and were excited about would not work. As a general rule, my advice is not to bring any crew gear with you that you haven't field tested at least a couple of times to make sure it works. But here are some more specifics.
First things first, do not bother trying to bring your own bear ropes or bear bags. If things are still they way they were when I worked there, they won't let you (or you'll have to check them out anyway). While the ropes are somewhat bulky, they are sturdy. While the bearbags are nothing pretty, they work and you are guaranteed to have plenty of space for food and smellables. I'm not saying that the system couldn't be improved, but don't forget that 30,000+ people use these every summer with little or no problems, you can't beat that kind of field testing. And as I said, you probably don't even have a choice. So save your money and space in your travel bags and use the ones Philmont issues.
Pots and pans are also an iffy thing. Certainly Philpots are not the lightest in the world, but they get the job done. The biggest thing you have to keep in mind is that Philmont meals are all one-pot affairs. So if you have more than 8 people in your crew, you are going to need a huge pot to cook all that food. Don't bother bringing anything less than 6 quarts in size, and really 8 quarts is best (especially for bigger crews). If you can find a lightweight pot that size, then ok, but otherwise save yourself the hassle and expense and just rent one of the Philmont pot sets,your ranger will show you what you need to take with you (cookpot, washpot, lid, spoon.)
Dining flies are a little easier to manage, but if you do bring your own, make sure you've had a couple trial runs setting it up and using it on a hike. And again, the Philmont dining flies set up with trekking poles are pretty lightweight and durable.
The only thing I definitely recommend you avoid checking out from Philmont are tents. I fact, if you want shave pounds off your crew gear, that's where you should do it. Save your money on all the other stuff by using Philmont's gear and use what you save there to make sure everybody in the crew has a good lightweight tent. Of course phil-tents do work, but they are so heavy (~15lbs) and require so many stakes (10-12) that they just aren't worth it.
I also want to reiterate what Nick says about pack weight/size. It's really a matter of the size of your pack, not so much the weight. Nobody is saying that finding ways to make your pack lighter is a bad idea. But the point that Nick is trying to make is that if you have too small a pack then you automatically exclude yourself from carrying a fair share of crew gear because it won't fit in your pack. In your practice hikes and preparation for your trek, make sure you plan to have a little extra space in your pack so you are certain to have room for extra gear. You will realize on your trek that there are unexpected things that you will have to carry that may take up a lot of room (extra water containers for dry-camps, larger food pickups, crew gear you forgot about etc.) plus there is really no overestimating how much space food takes up. And Nick's right, Philmont's not the place to show off your ultralight packing abilities if it means your crew has to shoulder more of the crew gear.