I know there's a long time to go but we've booked a holiday to Kenya which includes a short safari trip. I have the following lens available: Tamron 55-200 1:4 -5.6 Canon 70-200 1:4 l USM Sigma 70-300 1:4-5.6 Sigma 135-400 4.5-5.6 Kenko 1.4x Pro 3000
You seem to have a lot of overlap in focal lengths.
I would just stick to the one lens (less chance of dust getting in). Also, I'd go for something at the longer focal length (so probably the Sigma 135-400).
-------------------- Master of the Bench and Global Ambassador of the Brotherhood of the Bench Bench or No Bench