Sparker,
Have you ever of flywheel knockers? I use several different ones here on my 2 handheld two cycles. I read in Tecumseh engine service manuals that they made them for the larger mower engines. They are basically a solid piece of metal that is drilled and tapped to the thread size you need. This done deeper than current threaded shaft length as to not bottom on the shaft end. Mine are made of hex stock so I can easily install and remove them.
They are higher than the flywheel fins [much less chance breaking fins with a hammer] and are screwed on until seated, then backed off one thread [maybe two at the most], and you smack the knockers with a heavy hammer. This jars the flywheel off the taper. No damaged threads or mushroomed crankshaft ends. It might a few hits with the hammer depend how stuck the flywheel is on the taper.
As for over tightening that is why you should be using a torque wrench as over tightening not strip threads and not an impact gun, its damages the flywheel.
I prefer pullers but there are flywheels that don't have puller holes and these flywheel knockers work fine for loosening the flywheel.
