400 km? It's no problem :cool4:
And from Choum to Atar?

Choum to Atar is relatively straightforward. Follow the piste South - no GPS required but take a map! The going is rough (horrible corrugations if you go from Choum) but no sand of any consequence.

A carefully driven 2wd would be OK. Last section is on tarmac (and you will stop to kiss it).

2WD campers have driven NDB - Atar so it is possible.

2CV for Mauritania
 

"The short answer to all of your questions is "no". Sorry to be so negative!

One day I would like to try - perhaps with a stripped-out Renault 4 - but the reality is these pistes are not for normal 2WD's.
"

Euh ...Mauri not possible with 2wd's ? Take a look to the book "Mauritanie au GPS" : this guy have done a lot of difficult tracks in Mauri. with a "normal" Citroen 2CV.
2CV :the best car in the sand but with no luggage (or almost so) .
RR.

Yeah, but I think Monsieur Ribas is an exception, plus he did make one or two tweaks to his Citroen!
Of course it is possible - but then so are a lot of things!


Baby Renaults in action:
La 4L dans le sport auto - Paris-Dakar - 4L R4 Life