As of now, because there is only one portrait global layout I have to set it up again for every new game

That would be awesome if possible.
EDIT: Actually it might be simpler and more generally purpose useful if there was the option to save a layout as a new global layout, instead of only as one of the existing presets, or specifically for one game. That way you could use the same custom layout in 2-3 different games without having to set it up again. Essentially add a "Save As Custom Layout" and "Load Custom layout" to the Menu button in the Custom Screens setup screen. Probably could hijack portions of the code for save/load savestate buttons, but I'm not a programmer so what do I know?