Hello Jeff and others:
Here again I couldn't resist the temptation to join this discussion; As you probably expect I always want to refer to the historical data that I have seen over and over again in traditional frames. I have noticed many 8 by 8 vertical posts in barn frames intesected by girts coming in on the same planes from the sides, and in all cases the tenons would be slightly less than 4" in length because of the shouldering and to ensure that they would not bottom out against one another. In (most) cases the tops of the posts are held in position by the main upper plate, relieving the girts of any duty as far as lateral tension is concerned, these girts only duty is to be a wall stabilizer for the siding boards or panels. The framers would have only used 1 pin for attaching in a majority of cases. If your construction does not have an upper plate then the girts may have additional duties and have a more important part to play in the framework's makup.
NH