Answer

First, you are assuming that considerations of modesty are rooted in sinful thoughts on the part of the observers (members of the opposite sex. Or perhaps members of the same sex, if we are dealing with homosexuals). That is, on a deserted island there would be no laws of modesty. I do not think you are right about that (there is an article by my friend Nadav Shnerb on the topic: https://www.bmj.org.il/userfiles/akdamot/29/_1.pdf).
But sometimes there would be a prohibition here of "do not place a stumbling block," which does not necessarily overlap with the prohibitions of modesty. And of course it would not always apply, because there is a delicate consideration here regarding the balance between a person's right to do what he wants and the other person's right not to stumble—must the one causing the harm distance himself, or must the one liable to be harmed? This is a not-simple topic in the laws of neighbors in tractate Bava Batra. The line between them is subtle and complex. But no matter where the line is drawn, it is clear that in these considerations there is no difference whatsoever between women and men.