I suppose that is one of the advantages of a biesmeyer fence , I made a sled
that rides on the top of the fence with a piece of wood attached to the
side. then clamp the piece that you want to cut tenon on to it . set the
fence and slide the sled through ,flip the workpiece and do the other
side.....

then set the blade height, and using the mitre gauge cut the scrap off using
a block against the set fence to ensure the correct cutoff length .Do not
use the fence directly, else the cutoff will jam between the blade and fence
......mjh