With my 49" I use OBS + Mouse follow script + OBS preview window on laptop screen and share my entire laptop screen. That way I know the window size is suitable for others viewing from their laptops and the preview follows my mouse and you can tweak zoom levels and mouse boundaries on the fly. Also the OBS preview window opens on launch, without opening the main OBS window. So you never have to see/interact with the main OBS window/application again so it really feels standalone which is great.