Well, there are NSFW Terraria mods already existing. Some at Steam's workshop (they don't allow something too wild, but at least nudity should be there), didn't check what content they have. I've seen once a big site with presumably a lot of adult mods for Terraria even considered giving it another go because of those, but eventually decided not to and nuked the file with the link, can't find it now quickly - but hopefully it's still around.
Also there are also NSFW mods for Starbound, IMHO better game than Terraria. Just to mention Adult A.V.I.A.N.