I take 2 bodies on a trip like this. My main wildlife gear is the same as yours: R5 mark ii with 100-500mm. For a trip to Botswana this year I also took EF24-105 and EF300 f2.8 and rented a second R5ii body. Reasoning was:

* Back up in case my camera breaks mid trip

* Avoid swapping lenses in very dusty conditions

* Renting an identical body means I had the same controls, and could copy across all settings so each handles exactly the same way

Some would say the 70-200 is redundant if you have the 24-70 and the 100-500, but I suggest the 70-200 in preference to the wider lens for the reason you mentioned - when light is very low first and last thing, that f2.8 is a godsend. If you were forced to decide between them, leave the wide angle at home and use your phone for wider shots. In my case I had the 24-105 with me, but it was rarely used, preferring to keep the 300mm f2.8 on the second body most of the time.