I wrote up a quick patch that restores the panty removal and insertion functionality during the midnight sex segments for the demo. Most of the code was already still intact, so it was just a matter of pointing the game to the right places. It's not perfect, and you will probably run into some weird things, but it makes a lot more of the gameplay accessible.
Please note that I did not add any graphics to the mod. You will run into error messages for every missing graphic, but the game is still fully playable.