Are you planning on a soffit box on the side eve? For the gable ends pass the 2x decking the needed distance beyond the gable ends. Or better yet, don't do that just extend the strapping on top of the foam as the extension, allowing you to tie the side wall insulation into the roof top insulation.
I am starting to double strap the roof, two layers of strapping, so you get extensions on gable end eve.
Are you foaming the walls as well?
How important is the 2.5' of overhang?
