Blender technically already supports this. It’s just more tedious to setup, and you don’t have the ability to paint across multiple UVmaps:
There are also some issues with how blender handles texturing that might give you some trouble. If you texture paint with the texture slot in “material” mode, it will look at what texture you have selected in the shader editor as well as what UVmap you have selected in the property editor when painting.
In my opinion, the best thing to do is setup the blank textures and UVmaps in the shader editor ahead of time, then manually specify a texture and UVmap to use with the texture slot’s “single image” mode, and paint while the viewport is in rendered mode.
This probably won’t help with the texture memory issue you guys were talking about though.