Cutting past the front of machine

I want to cut box joints with the wood attaches to the front of my 3xPro. Right now the bit does not extend pass the front far enough to cut 3/4" thick wood.
The problem is that when you jog it to the front that it stops at the front brackets and wont go any farther. What needs to happen is that a spacer needs to be put between the router mount and the z gantry. If it were 3/4" thick would be great.
on My shapeoko3xxl with the Dewalt router it hung over the front almost 1/34"
Any ideas on how to make this happen
Thanks Jeff Peters

Such thick wood affords one the option of doing joinery cut flat on the machine — two simple techniques for this are:

and the simpler:

which has the advantages of not requiring special tooling, and allowing one to do a test fit and making simple adjustments to recut to allow it to fit.

I like this joint. I feel it is more a blind finger joint miter.
Took me a bit to get the concept but feel it is easy now that I figured it out.

By the time I need to use it again I may need a refresher, who knows? :face_with_hand_over_mouth: