Is it possible to align the viewport camera to the normal of a selected polygon?

Yes, you can...but you need to use Construction Plane.

1. Set CP to a polygon or set of polygons you want to be in a frame.
2. While CP active, in viewport top right corner click on Persp menu
3. Scroll down to Home and select 'C-Plane Normal'
4. Select desired Camera and lock it
5. In viewport click 'Spacebar + H'
6. DONE

Basically, Camera view will align with CP normal. Hope that helps!

Can also be done with Python, which you could put in a Shelf tool and access with a hotkey.