I'm looking to cut 3 pass-through mortises (2"x6" long) on each of eight large pressure-treated square timbers (8"×8" wide x 8 feet long) for a small post & rail fencing project.
I've cut mortises on smaller thickness using just hand tools (drill, chise, wood file). I can't justify buying a plunger router or drill press just for this project and hardware companies near me don't rent them out. My plan is to purchase a longer drill bit, drill numerous holes along the inside edges, chisel out an opening on each side, use a sawsall tool to cut around the perimeter, and use an oscillating tool to clean up the edges. This will take some time since I have 24 mortises to cut. Not needing a tight fit since the rails will be loosely placed inside the mortises. Any other suggestions on how to do this easily with hand power tools?