Desk top with bread board ends?

[wbrent [OP]]

I milled some ash a couple years ago and over the holidays dug out a handful of boards to bring inside. They dried nicely. Moisture meter says around 6 or 7 percent. Decide to clean up a few boards that ended up finished at 7/8" thick. Glued them together and now have a panel 32" wide by 67" long. In the back of my mind Im thinking my little office could use a nice desk. So maybe this will become the top. Need to do something to prevent it from cupping while I figure out what kind of base to build. So, is 7/8" too narrow to make breadboard ends? My tenons would have to be between1/4" and 3/8" thick. Is that going to make for too weak of a joint? Is it going to do its job of keeping the table flat? How deep would you make the tenons? The space the desk will go in is 72". No more. Im thinking of making the breadboards 4" wide. Would 2 1/2" tenons be about good for depth?
Or is that all a bad idea, in which case I could just screw some cleats to the bottom for now?

[Randy in Calgary]

I am sitting at a desk with breadboard ends. 3/4" white oak. The tenons were a little thicker than 1/4" and about 1 1/4" long if I recall. I only used 1/4" dowels for pins. It doesn't have to be crazy strong. If you offset the holes properly it pulls the joint closed, but doesn't put it under compression.
I've made several tops this way. No issues.

[Randy in Calgary]

I should add that I glue the front for the first 3 or 4 inches to keep things flush, and only allow the back to move.