I realize this thread is relatively old, but we're planning a 2019 Philmont trip for our troop. Something I've read elsewhere for dry camps is to eat your cooked dinner at lunch time near a water source. Then eat your lunch for dinner at the dry camp.
This would greatly reduce the amount of water necessary at the dry camp since you'd need none for cooking and cleanup.
Also, while I understand that Philmont mandates the use of chemical purification, would it be a good idea to take a Katadyn BeFree just to clean up murky water?