Bamako as entry point written on your visa will be okay for customs in Nioro

http://2.bp.blogspot.com/-6tuOTlezaf...0/DSC01729.JPG

We did that in 2012. I dont know if we miss the regular border or not.

It was not possible to handle the necessary paperstuff there, it use some time driving through keyes - to get every necessary stamp. Because we dont speak french - it was not so easy.

On a "usual" border you can complete everything there.

We got lost on the way - because the track vanished (while following the best visual track).. Ending with driving freestyle in direction of mali. We did change our route (planned was Senegal - Mali), we dont had GPS Source for that....

Surfy

Route betwen Mauretania and Mali is great. Normal tarmac Nioro-Ayoun, nothing special, even relaxing. The best for me is Kiffa-Kayes througt Kankossa. Nice track to do in winter (dry), sometimes difficult to find but very pleasent. Don't drive in night.
Another is Selibaby-Aouru with corrupt Malian soldiers. They don't leave you without 20-30 EUR.
If you can choose take Kankossa.