Nothing special, just cutting a hole out and extruding the edges outwards, and yea..trying to fix the topology in such a way it doesn't mess up the bake..quick maya screengrab:
I was making more versions, and adjusting the head more At this stage, only doing very basic clothes with the classic low poly and extrude, nothing fancy. Then, the beginning with Marvelous!.
Created a floating city kind of thing using nothing but a simple rounded rectangle shaped repeated at various sizes. Ended with a slightly extruded version to give it some depth.
If I create a cylinder I have to thicken the mesh with the extrude tool, to avoid" see-throught" when I importing the mesh in UnrealEngine. But maybe thats the only solution.