I would be curious as to how you arrived at your Roof design, and, why that wouldn't have suggested, or forced, a rafter to Plate connection?
Most of the Traditional Gambrel Barn roofs I have seen in the NorthEast U.S. have had the rafters broken across Continous Purlin Posts. But, your rafters are only 2" x 8"'s so it would seem, to me, that this question could Just as easily, if not more easily, be solved by asking, What would a conventional Carpenter do?
I would certainly not use a 1" peg, for you would, at absolute best, have but 1/2" checks on either side of your peg hole.
And, as Bake points out, 1" Purlins are, better refered to as Strapping.
I am all for Step Laps, but, it would seem, given the nature of the roof framing, and the dimension of the members, that Bake's Advice will likely be the truest for your particular circumstances.
