A nudist colony would not be so close to an area or be open in such a way that "lookey-loos" could even look in from the outside, much less make the loud comments Fred was making.
Furthermore, most nudists would be something Fred would cringe at rather than enjoy the view of.
Fred and Lamont are dressed as though it's cold out (it even appears that there's snow on the ground), but they discover an active nudist colony behind their campsite.