The two Indiana resorts I know of are the Ponderosa Sun Club and the Sun Aura resort. One is famous for holding annual nudist beauty contests with plenty of beer and truck drivers cheering on imported strippers from Chicago.
The other nudist club has a considerably more colorful past. It was once the home of Naked City and its eccentric wheelchair-bound owner/operator, Dick Drost. Years ago in my foolish youth I flew my then college girlfriend and another couple in a Piper Aztec E from the Kent State University Airport in Ohio into the 2300' grass strip that served as Naked City International airport in Roselawn, Indiana. My only recollections of that weekend thirty-plus years ago were the tacky, Bizzaro World plywood structures at Naked City, the shockingly young girls tending to the bearded owner in his wheelchair, and the fact that I successfully extricated the expensive, university-owned light twin from the short, unmowed grass strip and over the trees at the end of the runway.