I've not been down the West Coast so can't comment on game viewing there but I have spent several years overlanding (in a Land Rover) in Africa and a lot of time in parks in East and Southern Africa.

If your priority is wildlife viewing then your options are going to be limited in this sort of vehicle I'm afraid.

Firstly there are certain places where they only allow 4x4s to enter the park eg every park in Botswana and the Ngorongoro Crater.

As regards the roads rather than the rules I think you would struggle anywhere in Zimbabwe, and anywhere in Zambia except South Luangwa (see below). In Namibia you'd be fine in Etosha and Sossusvlei (up to a point after which only 4x4s can continue) but not anywhere else. In South Africa almost all parks are 2WD accessible, including obviously Kruger, KTP is the exception to the rule. In Tanzania you may be able to get limited access to some of the Northern parks but access in the South is more doubtful.in Kenya I can only think of a couple that are accessible like Hells Gate. In lots of parks you will get through the gate and to the main camp easily enough (because guests are transferred there in 2WD vehicles and use park based 4WD for game viewing) but if you want to self drive you will run into difficulties.

There are some big draw parks where you'll be able to get in but will be limited in terms of what tracks in the park you can take. For example the Serengeti, Masai Mara and South Luangwa all have a network of main/all weather roads that a 2x2 can navigate but many more tracks it couldn't. It will also limit your options on where you can camp in a park (ie you'll be in the main central campsites along with the overland tours as opposed to off in a bush camp somewhere).

I should say 4WD isn't the only factor here. Just as important is the ground clearance you have. The other massive factor is the weather, if you are in rainy season then even the toughest 4x4s will struggle in a lot of places. Obviously the rains come at different times in different places.

In short a lot of parks are only really navigable in a "proper" 4x4. There are still places you can go, notably in SA. The good news is that some of the cheaper parks eg everywhere in SA and Etosha are 2WD friendly. Also bear in mind that in some parks in East Africa park fees mean it can be just as expensive, even sometimes more, to self drive as opposed to taking a budget safari so somewhere like the Serengeti or Mara I would definitely explore that option.