Orange River - Source to Mouth

So... I have had an idea for quite some time now to do a trip along the entire length of the Orange river from source to mouth. So for those of you who are now wondering 'where the hell does the orange river start?' follow this link to find out. Its in the far north of Lesotho which is the first problem for me. I have never actually ridden in Lesotho before and in actuality I know bugger all about the area or routes. The idea is to follow the river as closely as possible all the way to Alexander bay. The thing about a trip like this is that it should take you through so many different environments and such fantastic areas that one will need a one whole bucket for that list. Highlights of this for me would be traveling thorough the most rough parts of Lesotho (which I have never done before) on to the semiarid areas of the Karoo, Gariep Dam etc, heading north to the Kalahari, Richtersveld, Namaqua 4wd Trail etc.. My research tells me the river is 2200km long which should make for a lekker 'short' trip that could be done in a week.

I now need to ask my fellow dogs for some advise and info for routes that could assist me in the planning of this. I think this may need some more planning than usual as the idea of keeping as closely to the river as possible may make it a little more challenging, especially in Lesotho - but I could be wrong. So hit me with whatever you may have. Also considering I'll likely be doing this solo and on a heavy laden KTM 690 fully dressed (oh and don't forget the fly rod) I'm not exactly looking for your ROA train goat paths