Just some perspective, but we have never split up our Troop FAK, its intact in the Scoutmaster's pack even on 50 milers. All told the Troop FAK weighs about 2-2.5 lbs including the bag. I believe its currently in a recycled AMK med kit bag that folds out and provides the modular approach to organizing contents favored by so many. (You can buy the empty AMK kit bags from campmor, kinda pricey - I have also found a close out of the AMK Professional series for $99 (reg $249) that included alot of good kit, a few expiring meds, plus a hefty bag). But that's for organization not so much for efficiency, except for stopping bleeding and treating shock and hypothermia, one thing you have plenty of in the wilderness is time, no one should be rushing around with a partial kit and rushing the treatment. I've never felt having my FAK in a zip lock hindered care along the trail.

fwiw my personal FAK for 50 milers closely resembles the Troop FAK, we're effectively doubled up, but I just can't resist carrying what I think I may need. My daily carry (on hikes and outings) FAK fits in a gallon zip log bag though, and while I haven't weighed it probably is on the order of 1 lb.