I'm with @Charlie H 72, and like him I'm no expert either.
It took me a few looks before I found out what you meant with the short grain issue but the exaggerated version clarified that. We're talking about a millimetre here, both in length and depth. If structural integrity depended on that very millimetre, we should have strict plans for all sorts of wood as their strength varies. Brittle woods should be left thicker than stiff ones and we should have tuners of various lengths to match the thickness needed for the most commonly used woods. As this isn't the case I believe there's quite a lot of headroom.
A bottom side headstock plate is a classy feature. Further, you could even make a separate volute piece to strengthen the joint if you wish, either contrasting or matching. Carving the volute piece so that it minimizes the end grain area would make a very solid glue joint, perhaps even stronger than a volute carved from the actual neck.