My normal kit for multi-day backpacking is a 60D, an 18-200, a spare battery, and a spare compact flash, plus a dry bag to but the camera into during inclement weather. The camera normally sits in a padded case (LowePro
?, don't have it with me to check model number) and if the weather turns particularly wet, off it goes into the drybag.... For a dayhike, the kit becomes a 17-55 and a 70-200F4.... and if specifically after birds I add in a 400F5.6.
I don't like superzooms, but when size and weight really becomes an issue I am willing to trade off some IQ for the ability to carry a good camera body. I find that 18mm on a crop is not wide enough in the mountains, but you can take multiple shots and stitch them together for those really wide views.... I find 200mm on a crop is not really long enough for birds and animals.... more mm is always good, but it gets heavy.
If I were shooting full frame on a hiking trip, the 17-40L would be the first lens into my kit. I think the second would be a 100-400. Most of your shots are going to be either wide or long and these two lenses will cover most of it. For the shots in the middle I'd either crop from 40mm or stitch at 100mm.