I don't think I'd do canteens, but I do have a couple of 48 oz nalgene bottles and a Snow Peak cup in the truck 72 hr kit. What I'd need is some way to carry them on my body. Of course, I also have the Jetboil in there. What I don't have is something packable to carry it all in.

In any case, neither the canteens or nalgenes are packable on the proteus proper - they're just too big. Could put one on a countycomm bag.