No problem. In fact, maybe any tsetse flies might be biting your backpack instead of you. Your backpacks will be on the floor so unseen by any animals.
We did have friends taking a South Africa/Botswana none Tauck tour whose Guide sent folks back to change bright colored t shirts to neutral colors. But on our last Safari a good number of our group wore bright colors like lurid pink and there were no comments. I believe some animals are color blind anyway.
Dark colors (black, navy, etc.) have been reported to attract Tsetsie flies (they are real biters and can bite through clothing), but as long as you aren't wearing the backpack, it shouldn't be much of a problem. Bright colors like those worn by the Masai people (hunters) supposedly scare the wildlife. How much truth there is to the second item, your guess is as good as mine, but we don't plan to wear clothes in either color category. I don't think you have anything to worry about. Maybe someone else will weigh in.
Masai wear red to scare off the predators (mainly lions) and there are blue flags hanging around in certain areas to try and catch/neutralize the tsetse's. My group had backpacks of all colors and no one seemed to have an issue because of them. They were on the floor of the Rovers, so I wouldn't bring a white one! Other than that, the only time they were outside was heading in to and out of the Rover. Not worth making another investment.
Comments
We did have friends taking a South Africa/Botswana none Tauck tour whose Guide sent folks back to change bright colored t shirts to neutral colors. But on our last Safari a good number of our group wore bright colors like lurid pink and there were no comments. I believe some animals are color blind anyway.