Morning Hans
I only joined this forum recently and stumbled upon your request. Yes you can safely drive that route with a 4×4 Fortuner. we have done it in groups a few times. Johan von W described a different far more complicated route from the East.
If you have not yet changed the front suspension to a longer travel more off-road type I would do it before hand. The Coopers are probably the best available wheels for this terrain. Best to deflate your tyres to 1,5bar from Fort Sesfontein onwards. That road is frequented by supply trucks and support vehicles servicing the lodges north of Purros. so, it is not a “lonely” road. I would also take with a snatch strap and proper u-bolts.
Fort Sesfontein Lodge is very nice and affordable to stay but the Warmquelle Campsite just before that is very good with hot springs to swim in and new well appointed ablutions and camp sites.
The timing of your trip is the most important. If after a good rainy season I would not do it before mid May. The issue here is more the road between Fort Sesfontein through Omanye to reach Purros. About 100km, mostly good road. Long stretches of that road is actually in the Gommadommi river bed. Mostly dry but not a good experience if alone and the river is soggy. Sesfontein is your last fuel point.
The distance from Purros to Kunene is about 150km one way depending on which tracks and routes you follow. I would prepare myself for sufficient fuel to cover 600km at 7km/L. That should be safe. You can work on a average travel speed of 50km/h excluding stops for pictures etc.
It is also important to have proper jack points and a high-lift jack. Water is important although you can refill at Orupembe. The lodges past Purros are all in conservancies and very unfriendly. The lodge at Purros are very helpfull and a good spot for sundowners. The community camp site at Purros is very nice, friendly people and good water with hot showers.
To access the Kunene river basin to the West is a bit tricky. You need to know your way around to get through the Hartmanns Mountains and Valley and then to decent from the high escarpment down very steep sand tracks.
If alone, I would aim for Camp Syncro which is on the Kunene and a nice photo trip through the Marienfluss and with proper directions to get there. I would stay at Purros and the next day pass Orupembe (enjoy an ice cold Windhoek Draught there) to aim for Marble Campsite 17,59″07 S 12,35″08 E. A real gem on the Khumib river with good fresh water and hot showers. from there through Red Drum to Camp Syncro.
There are some critical points you need to have to ensure you are on the “right” track because at some intersections there are quite a few tracks ‘misleading’ you in the wrong direction.
I do not know which Fortuner you have but if 4.0L V6 work on 5,5km/L and if 2,8GD or 3.0 D4D work on 7,5km/L. The Coopers are probably the best wheels for this terrain. deflate to 1,5B
If you are till interested send me a mail at info@rubdex.com and I will forward you some critical GPS points to double check your routing with.