I recently took Canon’s EF 400mm f/4 DO IS II USM to Africa and could not have been more pleased. It is small, light and ridiculously sharp, even combined with the 1.4x Extender III on the 50.6 megapixel 5DS R body. I purchase nearly all my gear from the kind and knowledgable folks at Roberts Imaging: https://robertscamera.com/.
Here is the equipment currently in my bag:
Canon EF 400mm f/4 DO IS II USM
Canon EF 70-200mm f/4L IS II USM
Canon EF 24-70mm f/2.8L USM
Manfroto Monopods
Gitzo Systematic Series 3 Tripod
Lowepro Bags
Sandisk Memory Cards
Delkin Memory Cards