Nudists have a word for folks who are new to nudism. They stick out like sore thumbs, tanned bodies with white butts, hence, cottontail.
It's always been a fetish of mine, and I've never found a website devoted exclusively to white butts on tanned babes. Clue us in if you know of any. Most of the 'tan lines' web sites aren't worth the effort.
I invite others here to post photos if you have any, but bear in mind the image policy DOES NOT allow vaginas or 'hair down there' and anus's to be shown. Can't blur images that show that either, ala Japanese mosaic. Think erotic, not explicit. It's a little dicey if a lady is bent over, exercise wise judgment.
If there's a good response from some of you, I can post more, I'll begin with a dozen or so.