Welcome to the FOG coyote.
I don't want to go through using a tongue and groove and slotted screw holes and pegged tenons.
Just curious why? These joints are definitely challenging but can be fun and extremely satisfying...at least the first couple are.
I made the center two mortises on the narrowest setting and the others on the 2nd setting. I then sprung the mating edge of the breadboard by sanding the center slightly concave.I then attached it by gluing only the center 2 dominos and leaving the rest unglued. When I clamped it down the center gap closed nicely making the ends really tight.
This is sounds like a good plan. For what it's worth, I would do it exactly the same way if I was to do this, not that it's right or wrong. Is the bread board end also quarter sawn oak?
Today I unclamped it and secured it to my bench with the joint overhanging the end of the bench. I smacked it pretty hard with a mallet a few times and it didn't budge.
With all due respect to your test, while it did test the strength or holding power of the domino, I doubt that it proved that the bread board would not separate under the internal stresses of expansion or shrinkage that the panel will.
My question is will this last over time. I'm fairly new to woodworking and have never done this before and as I stated I didn't want to attempt the traditional method. Thanks for any input.
Quarter sawn hardwood shrinks about 50% less than flat sawn stock so you have reduced the issue by half. A 36” wide top, made with flat sawn lumber, can move more than an inch with a 10% change in moisture content.
What is the moisture content of your quarter sawn oak?
In my view, moisture loss in a heated and air conditioned home over time (years not months) will affect the top more than anything else.
I would bet that your joint will stay together a lot longer than mitered corners without mechanical fasteners (dowels, dominoes etc.).