It kinda depends on what weapon you are planning on carrying. Is it a 2" five shot .38, or a 8 3/8" .44 mag?

Back when I used to backpack, I often carried either a 3" .357 mag, or my S&W 4013 in a small fanny pack, located in front, under the hip belt of my pack. I also like the GI "tanker" holsters, if I don't want to conceal the weapon. I "customized" mine with a different sholder strap, wider on top, with a mag pouch on the strap above the holster itself...