Hi Marc,
I just drove that route this week in opposite direction, all open, clear and dry. The ferry at Sendelingsdrift was still not running ten days ago, but may have reopened now if the Orange River has dropped enough. Oranjemund was a nice easy border crossing and a lovely little town to explore.
I made a data submission to change "deep water crossing" to "Flooding Possible with high water levels" - it was dry last week but it could flood if the river gets very high.
The Aussenkehr Nature Park (is the correct name - fixed on T4A now) only has signs up that you are entering so no fees to be paid - the locked gates are on the Quivertree/Canyon Route and the German Wargraves trail, keys and permits for these are available from the Spar in Aussenkehr.