This summer I'm doing a lot of photography-focused backpacking in mountains and forests. My primary considerations for choosing gear are handheld IQ, weight & pack space, and preference for weather sealing (when possible/practical). So far, I'm just about set on taking a 6D, 17-40L, 100L macro, and nifty fifty. Something tells me I'm going to need an option for more reach (animals), but the 400mm 5.6 available to me seems out of the question due to size. In the past I've used a 70-200 f/4 non-IS, but that was on a 7D.
Appealing to this forum's collective knowledge and experience, my question is whether I can get a 300mm+ lens weighing less than 800 grams that will beat the IQ of just cropping photos from the 100L. Or should I try and make do with the 70-200? Any thoughts? Thank you!