For most extended / non CQB games I rock an RRV without a back panel and I came up with this set up this morning. I took an issue foliage green Camelbak and a Condor go bag, which has molle strips on the back, and I weaved the strips through the side and bottom D rings.
I took it on a nice 3.5K Hike on the Bruce Trail by Mount Nemo in Burlington. It worked really well. I have a long torso so the go bag sat right in the small of my back I didn't even notice the weight.
The Go bag is my day to day E&E bag with various useful things.... Knife, couple flashlights, Mylar blanket, zipties, compass, pens, paper, food, 100' paracord some carabiners, small boo boo kit. There's some heft to it. The rig worked out quite nicely.
I also just ordered the Condor 3-Day assault pack for 24 hour games in tan.
Image Courtesy of condor
I also have a MEC internal frame pack for non-airsoft related pack needs.