Hey there!
Sure, you had a fantastic trip to Namibia and South Africa in a compact car, just like I’ve done behind the wheel of the same kinds of cars.

But, just like me, you had to limit yourself to what was accessible and avoid places that weren’t... We didn’t know if those off-limits spots were worth it since we hadn’t been there—no frustrations!
I’m not saying you can’t have an amazing trip in those two countries with a Twingo, just that you won’t be able to go everywhere, and you should factor that into your itinerary.

For example, forget about reaching Namibia via the Richtersveld, Botswana via KTP, Messum Crater, the Palmwag concession, northwest Namibia (where you also need to be pretty self-sufficient), the rustic camps in KTP, or certain parts of the Karoo, Mapungubwe, Mountain Zebra, Ithala, or the Cederberg, etc.
I’m not a 4x4 fanatic for these two countries—I often recommend a 2x4 or even a compact car depending on the itinerary and budget. I’m just pointing out the limitations.

For Botswana, it’s different. In a Twingo, you’re *really* limited. It’s frustrating, especially since the paved sections can be pretty boring. (Driving up from South Africa to Kasane on the main road is quite the slog...)
For Zimbabwe, I don’t know much yet except for Victoria Falls.
The possibilities with a 2x4 seem much broader, though, like in Botswana, you’ll have to skip parts of the country (all the wildlife parks except Hwange in the dry season). Less of an issue since the rest of the country is more varied and populated.
So, leaving Namibia via the Caprivi Strip, a quick stop in Botswana for Chobe on an organized excursion, then entering Zimbabwe and exiting back to South Africa.
For kids, the challenges are pretty similar everywhere. The barriers are mostly illusory.
You’ll need to keep a closer eye on them in the wild because of critters—big and small. (From scorpions to elephants...)
Well, camping in the bush definitely comes with more risks than staying at Skukuza! !

For adults too...