Kathy
Depends on how deep your pocket is, but there are wonderful places here in SA that is reasonable for your guys. Our Rand is currently about R17/1$ US.
You can hire a 4x4 or camper and camping over-nite for maybe $200/day. In Kruger, you can sleep in certain camps in the accommodation with communal facilities for about R800/night. We use it and it is clean. Check out
https://www.sanparks.org/
Note they charge a daily fee over and above the accommodation but there is a Wild Card that you can buy that maybe makes sense if you compare the cost of the two against one another. Accommodation is usually for two pax, even if you are single. Fuel is about R16/litre. You can do say 300 kms a day, that is 30 l a day or R480. There is an international airport at Nelspruit, 60 kms from Kruger. Kruger is totally drivable in a normal sedan, you do not need a 4x4 but any SUV or bakkie - your trucks - Toyota or Ford, is higher and just easier to sight-see from. Kgalagadi, you need a bakkie or SUV type, the sedans is too low for certain parts of the road.
I am sticking out my neck here - I "know" this lady from Flickr form way back and she travels to Kruger and Kgalagadi nearly every year for about 15 years. If there is someone who knows the complete
how to for one/two persons to get around here
in SA from overseas, she will be able to help. Her name is Katja Soehngen from Germany. She is on social media and a nice person, I am sure she will have valuable advice if you want to rough it alone and not use a touring operator - I would never use them because I stop when and where and how long I want to, with no schedule to keep.
You can also go the the private reserves and lodges and your per diem may go up to $1000-$5000., plus gratuitties plus drinks etc. Then they drive and dine you. In SANParks, you drive yourself, much better. We hate the bush taxis with all the tourists. It is more expensive but they try their best to let you see the Big Five.
As I have often mentioned on this forum, you are the only one who can decide what you want to see and do and where.
I have not touched the rest of Africa. It's your oyster, you have to explore and dream!