To what extent, however, we agree with indecent exposure laws (I don't, and it's a whole different argument), their purpose should be to protect against 'sexual predators' who deliberately expose themselves to others. If I come out of the shower naked and a construction crew working on the roof of the house next door happens to somehow spot me,...
Your scenario seems to include an expectation of privacy. If you've got that, nude away. (Wait, did I just say that?
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There's a glass storm door on the front of my house. Anyone on the street could see me, if I stood in front of it. No expectation of privacy there. If I nuded there, I'd expect I might get charged with indecent exposure or something. I would be deliberately (or at least carelessly) exposing myself to others. Not exactly sexual predation, but I don't see why the laws would be limited to that.
I admit, though, I'm no expert on the laws or precedents that cover that kind of thing.