I live in an apartment, so I don't have a backyard. However, when the weather is nice, I thong in my balcony. In fact, the balcony is shared, so it's not technically my balcony. My neighbors can see what I am doing in the balcony, but I don't think suntanning in a thong is prohibited. I guess it could be surprising to see a guy in a thong, but I don't think it should be a problem.