There are any number of lock Mitre router bits available in the woodworking
gadget catalogs made for stock of specific thickness. Generally they are used
in cabinet drawer construction.
The advantage to a simple rabbet joint is it can be cut with nothing more
than a saw.
If you dovetail your nails it is not likely to pull apart. If you want to get
fancy you can use stainless steel ring shank siding nails.
Of the 70 rabbet joint supers I made none are peeling open at the corners.
I purchase deep hive bodies because wide stock is too close in price to be
worth the effort.
If you size all the exposed grain in the corners prior to assembly with
thinned pva glue (titebond,elmers) things become far more durable.
For medium supers I stockpile short pieces of lumber 7" wide until I have
enough to spend a Saturday morning dressing stock and making supers.

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