Don’t be afraid to really shack it. As long as the tool remains tight
you wont damage the crankshaft. (see end of my video) Its important
to be sure the bolt remains tight so check it after each blow.
You want to try to get the heat in the flywheel so it expands and
then strike the tool before the heat works its way into the crankshaft.
Options are limited other that to step it up a little.
https://youtu.be/RWgE9XiIBnk?si=E_fZDo0SDhzAGMTM
However here is one-
https://youtu.be/FK5dAQaM-1U?si=4ElLWhn39Z5ecL4e
Tubs.
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.