Last questions then. Would I be alright with a 4' knee wall in this configuration? And if I were to use queen posts in one of the end bents, as in the first pic, how far out/down the rafters could they be placed? This would be in order to easily add an addition later on.

CB: I've only read that purlins need to be 48" on center. Can you tell me why the purlins on your king post frame look to be much closer than that?

Thanks so much for the advice...

Josh