Rename file you want to use to "save" and place in "Steam\userdata<steam_id>\345820\remote"

All saves give you a full inventory of items (minus food) and each save slot has the following additional powerups:

1. Silky Cream
2. No Upgrades
3. All Upgrades

All of the saves place you one room away from the boss. For Steel Maggot head left to get to him, if you try and exit from the right your game will crash. The game likely isn't beatable from any of these save points as I've just modified the save guy and not story progress.