I have a roof line that extends off the side of my garage 8.5 ft. from the wall that I want to lengthen three feet.  The depth of the garage is 24 ft..  I plan on anchoring four posts 8 feet apart to be the supports for the new extension.  Currently their are no supports and a structural engineer did look at it early this year on appraisal and said that it needed supports as is because of the length of the overhang and the snow loads in the area.  Taking his advice I want to put the supports in but I have a boat I want to store under the eave, hence I want to extend it out 3 feet more for coverage.  Can I do this?  I was thinking I could just extend the existing 2×6 rafters of the roof construction and tie them into the posts that I will be installing to enclose the new 11.5 ft coverage from the wall.  Is this sound engineering?

Thanks,

B