Hey, Dylan. You’re approach is well thought out. That said, how many tenons do you need to cut & how many could you cut by hand in the time it takes to figure out the jigs/make test cuts, etc?
Hand work is just as accurate, and in many cases, more accurate than by machine.
Re: Getting the tenon cheeks to match.
Don’t try to dial it in totally with saw cuts. Layout the mortise and tenons with knife lines using a square, get close with saw cuts, pare the cheeks to then knife line with a chisel. Leave tenon thick.
Brings up the point that tasks like this are as much about accurate layout as jig making.
Do the mortises first, tune up the tenon to fit using sharp chisel, rasp, block plane or combination of all 3. A rabbet block plane is the perfect tool for large tenons.
Think about cutting the tenons with a handsaw!