Sell custom printing solutions?

Hello, I have a client who would like to sell different articles of clothing, and custom printing on them. I’m having trouble wrapping my mind around how to do this in Woocommerce, if it’s even possible.

Basically he wants to charge a base price for the tshirt (say $12), plus $5 per logo. Then he wants to charge 15 cents per letter of anything they may want to write on the shirt. I already told him the letter part was just impossible because Woocommerce can’t take a string of text and create a cost off of that (I’m correct, right?) So he accepted that, but he still wants to charge a base price for tshirts and then a flat rate of $5 for a logo on those shirts. Is this even possible in Woocommerce? I’m having trouble figuring out how if someone orders say 5 shirts, how to make Woocommerce charge for the five shirts plus just one $5 charge for the logo. I don’t have a lot of experience with woocommerce add-ons, but if there are any that can help me with this, please feel free to recommend them.

Thank you so much in advance for any help/advice!