TomD
"You now have a slot that is the right size as the top, but oversize at the bottom, and lacking a lip for the dog. The properly sized wedge epoxied in from the bottom will form both face angle and dog ledge, and not be visible from the top."

You now have a square hole that is the right size at the top, but oversize at the bottom, and lacking a lip for the dog. The properly sized wedge epoxied in from the bottom will form both face angle and dog ledge, and not be visible from the top. With dummy dogs in place that can be held for gluing by just driving it in.