I tried going through Nambia as a solo-traveler and found out that it's very difficult to do. After hitching a ride from a honeymooning couple from Cape Town across the border into the Orange River region of southern Namibia, the hostel owner where we pitched for the night was alarmed that I didn't have any on-ward plans other than continue being a third-wheel on a honeymoon or be stranded with him for a week or more before another tour bus came through. Luckily, a "Whichway Overland Adventures" bus arrived at the hostel that night, and he nudged me to ask the driver to joining them all the way to Victoria Falls, Zambia. It wasn't routine practice to pick up passengers once the tour already departed, but after calling their head office and taking my credit card details, they allowed me to accompany them. I had already been to Victoria Falls, but since this was my only way to get through this vast and mostly barren country and the tour included the Okavango Delta which I was planning to do anyway, it turned out not to be a bad choice.
While I have a lot of scenic pictures of the stunning Sussusvlei Dunes, I decided to post one of my tour group since they literally saved me. I was on top of the world Thrilled that I could join them.
So my advice to solo-travelers is book an overland tour to go through Namibia. If you're not alone, there are plenty of people who drive through the country with a rental car.
For group tours contact: http://www.which-way.com/