I am repairing a bed frame, I need to make a mortise 2" deep, 5" long and 1/8" wide in the end of the rail for the bracket that attaches the rails to the headboard and footboard. (note: the width is the constraining dimension)

I thought about plunge cutting it with my hand held circ. saw but I am afraid I can’t do it square. I also thought about using my table saw but the peice is 88" long, I could never hold it vertical.

Any ideas?

I am currently building benches as part of my eagle scout service project and I need to know how to cut notches into a piece of 4×4 cedar wood for the arms of the benches to fit into the legs so the two can be screwed together. the cut will have to be in an "L" shape.

I am not allowed to use table saws or hand saws while building my benches for safety reasons.
sorry for not mentioning this earlier, i am allowed to use band saws and chop saws, can either of these instruments be used?