Use a knocker. You can buy one as a special tool or you can make your own. Find two nuts and a short bolt, the shorter the better, same thread as the shaft. Run one nut up on the bolt, followed by second nut only a couple threads, then run the first nut down against the second and jam them together. You just made a special tool.
To use, hand tighten the tool onto the end of the crank, lift flywheel and tap tool with a hammer as you suggested. Put the crowbar and sledgehammer away and use a small hammer, 12 or 16 oz. max. It is the shock that loosens the flywheel, not the bash. You won’t bend the crank. Showing knockers I made 50 Years ago, and never damaged a crank yet.
