Barry Irby
I have only hand cut a few dovetails in my life and none of them as good as the ones you do, so take this with a grain of salt.

I would have thought you would mark this off with the ends of the boards still square and cut the 135* bevel later, maybe after the joint was assembled.

I know you realize that you are one of the few people who will ever see these joints and perhaps the only one who will give a damn about the excellence of the fit. Therefore, you should do a fine job of it.

Years ago I made a table that had very slender legs. I punched the mortises for the rails with a hollow chisel mortiser. They neatly intersected. I suppose I should have mitered the tenons. I dovetailed them. No one ever saw them or knows they are there, except me. I imagine somebody trying to disassemble the table to repair it and what they will think if they manage to get it apart. I still smile when I think about it.

Put dovetails on that drawer that make you smile.