Routing the mortise is ok and a good option since its a stop mortise.
As for the tenon, something like this is best approached with the TS, IMO.
You will get a cleaner shoulder cut following the procedure below, especially in brittle wood like fir.
The technique would be as follows:
1. Scribe the shoulder and cheek lines with a marking knife or marking gauge. Bear in mind the cheek lines are guides you will fine tune it later.
2. Using a dado blade, and cutting just short of the line AND the depth, make the cheek cuts.
3. Pare down to the shoulder line using a shoulder plane or chisel. If you use a chisel, then clamping a guide to maintain 90 degrees is very helpful.
4. Using a combination of a block plane and a rabbet or shoulder plane, fine tune the tenon cheeks to fit. You can also use a large router plane this works very well.
In situations like this, I've noticed a lot of people remove sections of the tenon leaving an inch so that there are 3 deep tenons, one on each end and one in the middle.
The biggest thing is sneak up on it don't try for perfection right off the machine.
Last edited by DrRobert; 04-29-2015 at 09:28 AM.