I am using 5.5 inch wide cedar fence board as lapboard style siding on a chicken coop. The roof is a ~22 degrees shed style roof. I'm having trouble making the long cuts which touch the roof. The one cut I made in the picture below was much more difficult than I wanted it to be. I do not own a table saw or a sliding miter saw. I do have available a circular saw (which I used for this one cut) and a miter saw with a 10 inch blade.
What is the best strategy for making such a long cut?