I am not sure if you have done similar trails before but here is some tips and info for the Nossob trail:
1. The trail runs in two directions, one month from Polentswa to Twee-Rivieren and the other month from Twee-rivieren to Polentswa. You will need this information to make your bookings for the night before and after the trail.
2. You will have to be self-sufficient for a number of days relying on a battery system to keep your fresh food and drinks cold. The distance that you travel per day is not sufficient to charge the battery and by day 3 all your meat will be defrosted. Only take along enough fresh food (meat ) for 3 days. If can get a solar panel from the rental company it will help a lot, but not sure if many add this to the hired vehicle.
If you going to be away from camps without power for more than 3 days and no solar panel, you should considering buying tin food instead of fresh food. As you are aware the shops are not that close to go back for fresh stuff. Twee-rivieren shop does have meat available, but at Nossob for example fresh bread were delivered only after 2 weeks. They say weekly, but this can easily change to every 2nd week.
3. You will be require to take your own water for the trip and a bucket and shower head to shower at night.
4. Same goes for fire wood. You are not allowed to collect in the veld and need to bring along your own supplies.
Hope this info will help to prepare you and you will hear from some-one soon that can join you on the trip.