Not sure if others have come across this, but I picked one up on a whim and I have to say it's $30 well spent
https://www.infinitytools.com/lock-miter-master-jigs
I've been messing around over the last few months on the router table testing out different methods for drawer boxes, keepsake boxes, etc. Was interested in trying some lock miters and came across this. I know there are setup blocks, but I liked that this method would work for essentially any thickness (even if it was non-standard), and can help setup offset joints. Also nice that it works with other brand bits.
Broke it out this weekend, and cut a nice fitting joing on the first try. Can't beat that!