Have you considered the Sommerfeld jig? It is designed for router table use, as is the Leigh 16" RTJ400 jig. The Sommerfeld jig now comes with a fixed dovetail plate but tuning forks for variable spaced dovetail and box joints are available, as is a jig and bits for "organic" half blind dovetail joints.
https://sommerfeldtools.com/sommerfeld-s-dovetail-jig