Hi Olli,
After starting SimVimPanel (before loading the module), make sure the scaling option in the menu is set to "Real Size", and specify your screen width in millimeters (press Enter after typing the number). This should scale the panel to the intended real size.
If the scaling is still off, you can try specifying a slightly higher/lower screen width, and see when it fits.
Note that after the module is loaded, you can return to SimVimPanel's main menu by pressing "M", so you wouldn't need to quit when testing.
- Roman