My hiking bag is on the tinier side, but I'm quite fond of it.
http://store.lowepro.com/ca/flipside-sport-10l-aw-ca
Pros: Tiny* (narrower than a high school bookbag), it will hold everything the OP wants to bring, highly breathable for sweat, tripod holder (I put a 1L Nalgene bottle in there myself), rain cover, room for a camelback (that's where filters/keys/wallet go), deep enough to put some EF lenses (24-70 f/4, smaller primes, etc.) on their end rather than have to pack them lengthwise, will accommodate a non-gripped SLR with a 70-200/2.8 attached, etc.
* I've learned Tiny is sneakily helpful for hiking in that it sets a pretty hard limit on how much you can get in there -- a 20-30 pound load on your back is entirely doable in your living room as you test out how it feels, but it can be brutal 5+ miles into a hike. So smaller is better for hiking, IMHO.
Cons (as it pertains to the OP's original question/need): No internal bag access while you are wearing it / you have to lay it down to open it, and depending on how compressible your light jacket is, it might be tight for space.
- A