I don't have objections to the southwards extent of the Maghrib provinces, but I dislike the loss of Cyrenaica. I can argue some reasons:

-Cyrenaica was conquered by the Islamic Arabs by the first caliph, Abu Bakr, in 643/44, and became known as Barka after its new provincial capital, the ancient Barca. After the breakdown of the Ummayad caliphate, it was annexed to Egypt, although still under the same name, under the Fatimid caliphs and later under the Ayyubid and Mamluk sultanates.

-The Arab tribes settled in the south-eastern border of Tunisia (perhaps better called Ifriqiya which in medieval times was the area comprising the coastal regions of what are today western Libya, Tunisia, and eastern Algeria) were an outstanding factor in the political scenario of this region. In the 11th century the Fatimids favoured their settlement there as a counteroffensive to the rising independent power of the Zirids in Ifriqiya/Tunisia. These Arabs were also an important element of the military structure of the Almohads, who enrolled them in high numbers.

-Cyrenaica/Barka was a warfare scenario for the Siculo-Normans (conquest of Tripoli by the admiral Giorgio d'Antiochia in 1146), the Almohads (during the period of maximum extent of the caliphate), or the Ayyubids (campaigns of the mamluk soldier Qaraqush in the 1170s).

A possible idea for Morocco could be split it into two provinces:
-A northern province with Fes as capital and at north it borders on the Strait of Gibraltar.
-A southern province with Marrakech as capital and at west it borders on MTW Moroccan small sea region (I don't remember its name).