TM's will not be necessary. Once you pass the Secret Canyon/David Miller trail split which is well marked you start heading west up the canyon - Accept for dry river crossings, trail deviation is not much of an option. You cannot miss a camp site and this part of the trail is lightly used. I doubt there will be any other overnighters this time of year.What type of trail markers are you planning on using for the group?
I carried 5quarts. With no cooking/cleaning it was perfect for me for the overnighter but I'm not shy about my drinking From most of the reports there is water at the narrows at the end of the trail, another mile or so from where I stopped. If not there is rock pool water a couple miles back. Unfortunately the mile or so stretch where the camp site will be is on the side of the vertical canyon wall at least 100' above the floor/creek bed with no water.Looks like I will be packing water.
Special Caution; In this area you never know about the weather. Plan on cold nights in the 30's. Fortunately wind is not a concern due to steep canyon walls & trees. I did not take a tarp as I WOULD NOT DO THIS TRAIL WITH ANY CHANCE OF RAIN or recent rains. Watch your pack weight & know your equipment, this is NOT an easy hike. If you must hike the FR to the trail head you have doubled your distance and although not technical neither is it level - after a while you begin to fear the downhills as they can be almost as strenuous as the uphills when loaded and only mean an uphill is next. Finally, if it calls for rain a few days before or during I would abort. If you would like my email or cell phone PM me.