I currently own a Lowepro Slingshot 100, and it is currently at capacity with my 3 lenses (Tamron 17-50, Canon 100 macro, and Canon 10-22 with 430ex speedlight).
I recently purchased a Feisol 3442 tripod (carbon fiber and about 19" long folded) and would like to attach the tripod to the bag secure enough that it would work on a wilderness day hike.
Aside from that, I would like something that could accomodate the Canon 135L (a lens im looking to purchase someday).
I have used and highly recommend Lowepro's Off Road Camera Belt Pack. It easily carries my Canon 30D with 17-85 mm IS lens and 70-300mm telephoto. It comes with two additional lens cases that attach to the case, there has been enough space for me without them. I wear it around my waist and it is comfortable to hike in. I have used it in a variety of conditions and environments, mountains to the desert and everything in between. It can easily be worn with a day pack. The fit is good and secure. It is top loading which gives me quick access to my gear, when the top is latched but not zipped shut, for those spur of the moment shots. It is not listed as "water proof", but has done an excellent job keeping my gear dry in the rain. I have used it in the snow and have had no problems with moisture. While I do not find the following to be negatives about the off road you might. So, here they are and you can decide. First, when the top is closed but not zipped you can accumulate dirt, leaves, pine needle etc. I do not know how much "bushwacking" you do an your hikes. It is easily corrected by zipping it shut. Secondly due to the way it is carried, answering the call of nature or tying your boots can be challenging.
I use the Lowepro micro trekker 200 backpack. I have beat this thing up, and it is still working great. It isn't waterproof, but it should fit all of your lenses and camera. It has a tripod mount on the bottom, but since it is not on the side the tripod tends to stick out pretty far. That is the only con. It could probably be modified so that you can mount it on the side.
Personally, I have never found a camera backpack that I liked. I found them either too bulky and after several hours become VERY uncomfortable. I'm 6'3" and most packs are designed to fit people of "average" height. My recommendation, if you are serious about hiking, is to find a good day pack at a local outdoor store and mod it to hold your gear.
Check out REI. They have a lifetime satisfaction guarantee on everything they sell. Good luck!
