I presume you are taking your vehicle??!
1. Morocco - no worries at all there
2. Mauritania - since I last went the visa issues have changed & seem to continue to do so ...
3. Senegal - if your car is over 5yrs old you will have issues taking it in - Javier on here is good at explaining that ... Rosso is a pig of a border crossing, but don't pay them a thing if you can help it!
4. If you intend to do the Trans-Gambian, I would imagine crossing into Gambia and out again could be interesting, their border officials aren't much better than Senegal's.
5. The border at M'pack/Sao Domingos; I've not heard any recent reports but a year ago the taxi drivers really sped down to Sao Domingos from the G.Bissau immigration due to ambushes .. a few NGO vehicles have been targeted in the past - I would check up on safety issues in Ziguinchor to get the latest - Luiz, the Consul in Zig is an excellent source of info!