I recall in the past, the I joist manufacturer did not allow too steep of installation as the joists would begin to act lile a column and the allowable stresses would not apply.
Perhaps this has changed in recent years. I've not seen anything about it lately. I just thought of it while reading the suggestion about TJI's full height.
I see that you wrote you have discontinuous framing members so I suppose long pieces (such as you could get with MWJ) are not needed. Like I said, it just came to mind.
While I'm thinking about it, I'm not sure the roof "diaphram" will even act like a diaphram. Will it? The wall on the leeward side is fastened at the bottom edge to the foundation isn't it? Of course, it is on the windward side too. I wonder if there might be a need for some sort of diaphram on the inside of the building (maybe at the level where you describe the rafters are discontinuous).
Just wondering. I'm sure you have been thinking about this longer than I have. I'm just trying to visualize how either one of the sides of the A frame will actually be engaged like a diaphram. I don't think the thing is going to be stable without some interior shearwalls and (probably) a horizontal diaphram in there too if the rafters are not capable of spanning bottom to top and anchored properly to the foundation at bottom and to the opposite side rafters at the top.
Think about it....