You didn't mention what time of year you're going to do this (wet season or dry season makes a lot of difference!), and you didn't mention how far off the main road you're planning to go by yourself. Keep in mind that across Botswana (probably other countries too), unless you have a satellite phone, you're not going to have a way to communicate most places far from towns if you get stuck. And unlike South Africa, it's not at all paved / tarred roads through the Kalahari.

I was on a fly-in Safari just north of the Kalahari in February and not one but two guide 4x4s got stuck in the mud. And it took us a couple hours just to get one unstuck, and they had to send a tractor the next morning to get the other one unstuck.

Then I was on a fly-in Safari in the Kalahari and we saw a big rut next to the road and asked what it was and the guide explained that a big truck had gotten stuck there recently.

And if you get stuck, what does that do to your tight schedule?

I self-drove in Kruger and Addo Elephant National Parks in South Africa, and it's night a day the road conditions in South Africa vs the road conditions in the wildnerness of Botswana. (Note that around Kruger, right up the border at many gates, there's real towns. In Botswana, there's no "civilization" (as you're used to from anywhere else) in much of the country, it's intentionally left wild.

So be careful extrapolating from driving experiences in South Africa to other way-less-populated countries north of there.