Originally Posted by Tim Cullis
The problem with your scenario is that somebody else is taking the vehicle back, and the original import is tied to you. This can't normally happen, though death of the rider might be an exception.
This part of the problem can be solved by picking up your friends in Dakhla, drive together (with your van and bikes) to Mauritania. You leave Morocco with your car, one of your friends import the car into Mauri. Find a place to park your van in Nouadhibou (one of the campingsites). Then you can go back into Morocco as planned and your friends wander off into Mauri.
This will cost you only a visa for Mauri (at the border), maybe a import fee for bike in Mauri, possibly some hassle at the borders (leaving Morocco with car and returning next day with bike can raise some eyebrowsers) and a long solo trip back from border to Dakhla but gives you probably one or two extra days to spend with your friends.
On their return your friends will import the van into Morocco, pickup your bike and leave as planned.
bart & sophie