I am building an office and am considering installing 1.5 inch thick rubberwood butcher block top. [Here](https://imgur.com/gallery/L2wcT3r) is what I have completed so far. The right and left outside corners will sit on a cleat, but the inside corners will be floating unsupported. How can I join them like [this](https://imgur.com/gallery/PDkVv3W) that will account for wood movement but also be strong? Will glue and dowel joints work fine, or should I go full breadboard ends?