Back when I was parting trucks I made a tool for holding the flywheel (works coming off or on by locking against the starter bolt). Frees up your hands for other chores as described. A few minutes in the shop paid off for me for this job, a stuck engine will of course not need this approach.
https://www.flickr.com/photos/advance-design_parts_co/11594053183/in/album-72157631868452754/
https://www.flickr.com/photos/advance-design_parts_co/11593841395/in/album-72157631868452754/
I had an old ring gear but you can just notch flat stock to similar effect, good luck!