I just finished a pack I plan to use on the AT this year. Previously, I have used packs in the 12 ounce range made mainly of 1.3 oz silnylon. The problem is the abuse a pack gets on the AT and during transportation to and from the trail, including hitches. I felt something stronger might be better, even though it might weigh more.
This new pack weighs 21 ounces. The main body is Spectra grid fabric weighing about 4.5 ounces per yard. It has a large sleeve pocket and a pouch pocket on each side to hold water and fuel. The sleeved pockets will protect the pack if a bottle leaks, and net bottoms will let any leakage drain. The sleeve construction permits compressor drawstrings to work under the pockets. (A frameless pack must be packed tightly, and loads can vary radically on the AT.) A large pouch pocket with a liner and net bottom on the front of the pack will hold the ponch/tarp, stakes and groundsheet when wet and otherwise to keep the raingear handy. A detachable possibles pocket on the front accepts a cord shoulder strap for carrying it separately on public transportation. The main compartment is a top opening, roll-down straight-through bag 12X8 in cross section, 39 inches high. The top 16 inches are 1.9 ounce silnylon. The bag is highly contoured for a close fit.
I'll give a report on this design works out. Maybe next October.