I've been to Moreson Ranch, actual fact I'm heading back there in 2 weeks. The SWAMBO and I really like it there, its clean, you have you own ablution which SWAMBO really likes. Getting there is easy, bit of gravel road to travel on which is in good nic except when we've had a lot of rain. They do have a 4x4 trail there but I've never attempted it myself (not sure my standard highway tyres will make it).
I've also done De Wildt 4x4 a couple times, never stayed there though, didn't know you could. 4x4 track is great fun with chicken routes on most obstacles for when you not feeling so confident.
I've also done B'erakah near the vredefort dome. That is an amazing trail which I highly recommend everyone should do at least once. Elephant Hill (I think thats what it is called) I gave a miss. Seen a few cars not do so well there. I've also never stayed at B'erakah.
Keen to see what the other places are like seen as we just bought an off-road trailer and are trying to make it a rule to go camping at least once a month even if it is just for 1 night so places near jhb are ideal.