Welcome to our crazy corner of the internet. Hope you enjoy your stay here.
We where in the RNP last August. It was amazingly green as the area had exceptional rain.
To answer some of your questions, the roads are mostly along dry river beds. Thus the roads are sandy. Some sections are quite rocky, and in places we drove down riverbeds with rivulets running down them. There are also some bad corrugations on the roads.
A 4x4 vehicle is not a necessity, but I would suggest one. We met a family traveling in a VW Kombi.
Fuel is only available at Sendelingsdrif, although supply is not guaranteed. As BB has suggested, fill at Port Nolloth or Alexanderbay.
We stayed over at Pokkiespram and De Hoop. The camp sites at Pokkiespram is in the riverine bush. You can hear the river, but not see it. Just watch for the resident vervets, they tend to raid campsites. Ablutions is available but showers are cold water only.
At De Hoop the camp is also on the banks of the river, with lovely views of the river and surrounding mountains. Ablutions are similar to Pokkiespram.
We visited Kokerboomkloof. The camps are lovely situated amongst giant boulders. Here you have to supply your own water. There are chemical longdrop toilets available here. We will definitely spend at least one night here when we visit again.
Richtersberg is also on the banks of the river, some 8km upstream from De Hoop. The camping sites are on thick riversand.
The direct route between the two camps is next to the river. This route is more serious 4x4, especially if there was rain. My parents where in the park in April last year, during the rain. This section took their convoy 4 hours to complete, compared to the 45 min it took us in August with 2 vehicles.
In some places the road are very narrow, like on Browns pass (Also known as Akkedispas). In places the road is only wide enough for a single vehicle. So if you have to let another vehicle pass, look for an appropriate place to pull off the road. Remember the rule off thumb, vehicles going uphill has right of way.
The campsites at Sendelingdrif where still being laid out when we where there. It should be done by the time you get there. SANParks is busy with upgrades to Sendelingsdrif.
To visit the wonderful park you need to be self sufficient. I would suggest you carry enough water, the water available at De Hoop for example is not fit for consumption.
We traveled with 2 vehicles. However as BB stated, we also met a number of vehicles on the roads, but there are roads that is more remote and you might wait a while if you do run into difficulties.
Your vehicle is more than adequate to travel to RNP. AS long as it is mechanically sound, you will be fine.
I suggest you get hold of the Info Maps map of the park. It is available from most outdoor stores. You are supplied with a map when arriving at Sendelingsdrif, but the supplied map we got was a photocopy and was not all that clear. A GPS would be a good addition, but remember, GPS means nothing without a decent map.
This is a magical park. It is amazing to see the plants growing in such an arid world. One of the nice things of this park is that you are allowed to leave your vehicle and explore on foot. Just ensure enough hydration (yes it gets hot even in winter), and mind the snakes and scorpions.
I am sure you will not be disappointed visiting RNP.
Please feel free to sent my your number via PM, and I will gladly share more off our experiences.
Just one question from my side...... Do you mind if I tag along?