Hello @trix, and welcome to the forum!
I hope you don’t use Android, then you are able to install and use the following plugin to split your canvas in customizable ways:
Tile Grid: A plugin for creating customizable guide layouts for storyboards, tilesets, and more
Also Arrange 2: Universal alignment tools for all types of layers is a versatile tool, but I can’t say if it is useful for your task.
Michelist