When I was working on the small isometric game ā2.5Dā in XNA, I found it necessary to have a separate version of WinForms that would simply display 2D from top to bottom using GDI. This was due to my inexperience with XNA and my (relative) comfort with WinForms.
This approach also had a useful side effect to ensure the separation between logic and rendering code. This made it easy (at least for me) to check the changes without worrying about how to handle the aspects of XNA rendering.
This may not be exactly what you had in mind, but it might be something to consider.
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