It did occur to me that I could also get a mortising gimp. Each gimp with their own dedicated task. but that's taking it too far. I can easily cut the mortises myself. In fact I have become one with the mortiser during project Easy Rider, really enjoyed firing these in, and the machine has been purring like a kitten.
And here's how the rails dry fit into position between the front & back stretcher, these bad boys will receive some kind of shaping treatment of course. Glueing up will be another matter, but very happy with the fit. Best day in the shop ever. I had to stage a small celebration.