I downloaded HoMM 2 off of GOG and want to speed run, but I can only have the game window super small, or full screen. Both don't work with live split, how did anyone else get the timer and the game together?

When I ran my game (years ago), I used OBS. There's a screen capture feature that let's you record a portion(s) of your screen for your livestream. I kept my game in windowed mode (I think 800x600) and LiveSplit on the same screen and was able to do it that way. In LiveSplit, I know you can set inputs as global to work when your playing. Set your combinations of keys to something not used for the game (like CTRL+Right Shift+L) to start your timer, set your splits, etc.