This isn't rocket science here. Don't over think it. There is no bolt per say. It is a nut, more precisely the threaded clutch that holds the flywheel against the taper. Basically you don't use anything on the tapers as you can get things out of spec. Especially no oil or grease. Must be assembly dry and clean.
One last time. The clutch, spacer, and washers is what holds the flywheel in place. The powerhead must be fully assembled in order to hold the flywheel. The clutch is torqued to approximately 10 ft-lbs. Since you mostly don't the clutch tool (most of us don't) you just snug the clutch down. It does however requires a piston stop to do this. Rope insert through the spark plug hole is what some use for a piston stop but can get hung in the cylinder ports so a regular piston stop is preferred method. Operating the trimmer with the trimmer head and shaft will finish tightening it.