When I'm camping or hiking nowadays I generally carry my sidearm in a Hill People Gear Kit Bag or Runners Kit Bag. I suppose it says "GUN!" a bit more loudly than a lumbar pack but on the trails it's never garnered a second look. It's super comfortable and surprising about as fast to draw from as IWB. The regular Kit Bag has lots of room, and it carries the load very well. Without really overpacking it I can carry a full sized hangun (even an HK USP45 Tactical with a Surefire X300 Ultra!), spare mag, my Surefire E1B Backup flashlight, a notebook & pen, assorted fire gear and a pair of gloves. When I camp alone in more remote places I sometimes wear my HK P30S IWB and carry an HK USPf9 with an Inforce APL in the Kit Bag.

NOTE: No affiliation with HPG, just really like their stuff.