Thanks all for the positive comments.
One thing we found was that Sendelingsdrift (SD) and Potjiespram (PP) were the only camps west of the 2 passes, making it a bit boring to do the same roads each day, so on the last day we explored the river area near PP. At one place there was a strong smell of cat wee, so we presumed that an invisible predator had marked its territory. Next time we will camp on both sides of the passes.
The river area yielded some very nice lookout spots, giving varied views of the river's character. Some being narrower, fast flowing bits, but mostly wide meanders with islands disguising the main channel which seemed to be on the Namibian side.
The river is the life-blood of the park and provides riverine forests on both banks that house vervet monkeys, the only wild animals saw in 4 days. Our neighbours had obviously fed them, as they tried to get into their tents and had spread their garbage bags across their campsite. A few well aimed near misses with a catapult kept them out of our campsite. We packed all our food and garbage into the vehicle every time we left camp and there was no damage to our tents.
The mountain scenery was stunning, with much quartz in evidence, and some fallen boulders looking like they had been hand chiseled. The dry river beds used as roads often had streamlets running down.
In camp, the birds were shy, but we spotted many Cape White-eyes and red-eyed bulbuls, occasional Cape robin chats, European & swallow tailed bee-eaters, Cape & pied wagtails and lesser double collared sun birds. Otherwise birding was a bit slow, other species being grey and goliath heron, gyppo goose, pied kingfisher, moorhen and pale winged starling.
We left home on Monday morning having had a real chill out. The bacon and eggs, chocolate and granny's biscuits were finished, but some of our drinking water was undrunk, some 2 minute noodles and provita uneaten, some Amarula left and enough petrol to get back to Port Nolloth.
Observations: We only travelled in the west half of the park. We saw few solitary vehicles, mainly groups of 3-5. The park was fully booked over the long weekend and it appeared that people did not stay where they had booked, De Hoop (DH) was favoured. There was hardly an official presence except at SD. The park was litter free and courtesy reigned. Spend the first and last nights at SD or PP, and then move on to DH or Richtersdrift, at least 2,5 hours away.
Highlights: The stark beauty of the terrain, rock formations, PP campsite, DH campsite, the Orange river, challenging driving without wrecking the vehicle, halfmens, the stars at night, good company
Disappointments: Lack of information (maps, signposts etc), no souvenirs, no wild animals, small variety of birds, mining evidence, goats in a national park, saw no scorpions of snakes.
Conclusion: We will definitely return in a few years time in a group, and explore the east half, but also revisit some special places.
Acknowledgement: To my wife's usual stunning photography - keep going Linda!