Thank you, I'm glad you enjoy it! To see fox boi naked you actually need to be on the truth route and have high affection points with him. I've been debating on making a guide, but haven't decided on the best way to go about it just yet. In the mean time:
Spoiler
You will need to have the highest available affection points with him at that point in the game. To get this make sure you choose "I remember" > ask the orb all three questions (grasp, between place, who are you) > "Knowledge" > "Truth" > "Magic" > "Yes" > toast "To Magic" > "Cuddle with Silas" (You can also choose "Someone Sleeps outside" > "Me") > "Joke" > "Go Tell Silas" > "Go in"