I thread a nylon holster through the waistbelt stabilizer strap. (Cross draw) This allows instant access to the gun. The holster rides on the outside of the pack waistbelt.
I dont buy a pack unless I can thread a holster through some type of strap on the waistbelt. Sometimes this involves some creative nylon strap rigging in addition to the stock belt stabilizer strap.
I also carry an extra nylon holster and light nylon belt, (2.5oz), for when I am at base camp and pack-free, this way I dont a have to disassemble my holster system every time I camp.
I have tried most of the fanny pack systems and dont like them for several reasons.
First, they make deployment slower. Most bear attacks happen VERY quickly. Fumbling with a zipper or any kind of covering is a liability. Getting a gun out a holster and accurately firing it at a charging bear is a crapshoot anyway, why make it worse by using a purse?
Second, they get in the way, and are hot. Having something large strapped to the front of you gets in the way when you are climbing and scrambling. Your knees are always smacking into the thing. Chest rigs get in the way less, but they are even hotter than waist packs.
Third, they are one more thing to put on and take off. The more I have backpacked, the simpler I like things. I often stop several times when I hike, before I arrive at my campsite. I always take off my pack when I stop. Having to strap another piece of equipment like a gun pack on, and around, your torso, while already wearing a pack with a waistbelt/shoulder straps/ sternum strap, is cumbersome and can be very uncomfortable. By the third time in a day, it gets old.
Another thing to consider, if you do take rest stops, and take your pack and gun purse off, youd better remember to put that thing back on! Ive seen many extras left behind on rocks through the years. On the other hand, if your gun is always on your pack belt, you will never leave it behind.
A lighter smaller gun makes a difference in ease of carry. Going from a 47oz Colt Anaconda to a 27oz S&W Alaska Backpacker made a huge difference in comfort. The Colt used to get really annoying after a few hours and miles. Now, I hardly notice the S&W.
Sorry I cant post a picture of my belt rig right now, maybe later.
Now, having said all that, I do have a couple of waistbelt/purse holsters that I use when I am not wearing a pack, out amongst lots of people and it would be prudent to keep things under wraps. Combat fishing is a good example, as are day hikes along more used trails. But when I am backpacking, away from civilization, I holster my gun.