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I just ordered the Berlebach 50031, which is more of a table top pod, so maybe not what you are seeking.
The size is minimal, only 10.6" folded. It will go almost to the ground, 2.6" to 13.8" tall (plus head and camera).
I use a smaller LowePro Flipside 10L, which will make it very reasonable for mushroom hikes, or taking landscapes (just find a rock to put it on). I haven't used the tripod yet, but it seems very solid, rated for 17 pounds. I've got the smallest RRS head, the BH-25 and B2 mini-clamp, which I plan to move onto the Berlebach when it arrives. I think it will support my 6D + 14mm Bower, or hopefully 6D + 100 macro combinations.
I also agree that a comfortable pack will make a huge difference in comfort when carrying several lenses, tripod, accessories, water, food, etc. BTW, the Flipside series allows for a water bladder, which you definitely need if you are doing the Grand Canyon. Have a great trip!