I also second this.
I am looking for a way to achieve this.
Maybe tweaking some ini file is the way to go, but my understanding of scripts is close to none, so
I found some SWS actions like the following which sort of can be used like the screensets already built into Reaper.
SWS: Save current arrange view, slot 1
SWS: Restore arrange view, slot 1
and so on up to 5 slots each.
The problem with these actions is you can't save them to a project.
They are effective until you close the current session.
I know I can set them each time I open a session, but that sort of defeats the purpose of having screensets in the first place.
Certainly a welcome revision it will be.