While great for the consumer to have a four day cruise to Cozumel from Galveston, and include Costa maya ( axe Progresso) on an Oasis class ship, this may hurt the seven day sailings also on an Oasis class ship.
It would require a variety of seven day itineraries to maintain interest. Belize is working on a port island that will be a destination onto itself. Maybe send an Oasis class from Galveston, Jamaica, Belize, Cozumel then home. Or take somehow stretch it from Galveston to the private port in the D.R. and include Jamaica.