Hi Forrest!
Some common ways to panel the shorter sides with gable peaks;
1. Use long boards all the way up.
2. Break off where you say, even with the nailing batten. Either with a flashing that goes under the upper panel and over the lower one, or set a nice "waist" (a horizontal board, either completely smooth or nicely planed) and place flashing both above and below this.
If I understand you correctly, you intend to have the gable peak panel overlap the lower one (?).
If you then plan to place a 45x70 on top of the lower panel to cover the end grain and have something to nail into, and pull the upper panel slightly below, I definitely think that should work. Just saw the panels at a 15-degree angle so you get a drip edge.
I think it's a creative solution!
If I've understood you correctly?
Good luck! Johan