Unless you are going to rent for your trip, and risk fumbling around with a body you have never used before, I would suggest you buy something at least two months before your trip. You have no EF-S lenses, and you made no mention of shooting high speed action events, so your obvious choice is something full frame. You can take really nice pictures with a 5D classic, let alone newer models in the 5D line. It would seem prudent to consider a 6D, which is available today at bargain prices compared to its introductory price. I have taken excellent picture of raptors in flight with my 6D and a 400mm f/5.6 lens. I know I have no need for a 50 megapixel body now or in the future for what I shoot. Don't be obsessed with the latest and greatest body, as if it will magically improve you output. You seem really focused on fast lenses, yet you have nothing over 135mm. Depending on what you may find you want to shoot in the future, after a FF something purchase, consider a longer zoom that will work with a Teleconverter 1.4X version III. That could be either of the 70-200mm IS lenses. I have both the f/4 and f/2.8 II. Both work extremely well with the TC III. Then take both bodies with you on your trip, and however many lenses make since to you from a bulk and weight stand point. I recently returned from South America where I took a 6D and a 60D, plus a 24-105mm f/4 and a 70-200mm f/4. That covered all my needs, shot 85% with the 6D and 24-105mm, and had two bodies and two lenses incase something broke. (Nothing broke). It was also convenient that both bodies used the same memory cards and batteries. That was a major issue in keeping the quantity of equipment under control. Unless this is a paid gig, you want to enjoy your trip and not be a slave to your hoard of equipment. Enjoy your adventure.
