The German carte grise (French name for ownership paper) will probably have the date of registration expiry on it. This is an issue. Maybe customs wont care, maybe they will.
You can hope they are ignorant of these matters, but I suspect that this is not the case - Maroc is a favourite route for European car export to Africa, so my guess is they know the rules very well indeed.
You need to know first, if Maroc will allow a vehicle in with temp plates.
Then second, do you need a carnet for Maroc? You have researched this question yeah? Cos that is a dead stop on your plans if so - you can't get a carnet on a temporary export plate.
These are the two hurdles I think. France and Spain, no problem.
Sorry no good news, but clarifying the problems may be of help.
Around the world 2000-2004, on a 1993 Honda Transalp