Hi Tom, I'm sorry but currently there is not any way to change the arrangement of the viewports like you're asking. I would like to add something like that in the future at some point though.

But one thing that can cause difficulty with something like having 2 3D views is with some mechanisms like the PDF export where you pick which view to use for the projection for the export. With 2 3D views it could be weird in things like that to have "3D" listed twice without really easily knowing which one was which.... So I'm not quite so sure how that specifically would really work out as compared to just being able to change which spot a particular viewport was located in.

- Michael