From Nouakchott to St.Louis de Senegal by car

My husband and I are in Nouakchott and plan to hire a car to drive across the border to St. Louis de Senegal. Would anyone have any suggestions and comments about security issues (I am a US citizen and he is French)? Also, any suggestions on how to hire a car with a driver to take us there? Can we cross across the border with our suitcases and take another car there? Or will the Mauritanian car be able to cross over with us? Any suggestions welcome!!. Thanks in advance!