For a third connotation that is close to the GP's, think of a coach telling his players to hustle on the basketball court. To me, that means they need to play hard and quick, not that they need to try more to bend the rules, take advantage, etc.
That's interesting, I always assumed the coach was actually suggesting they try to bend the rules and do whatever's necessary to win, but your interpretation makes more sense.
You could play the game without hitting the ground, but if you wanted to hustle and win, you had to get your clothes dirty.
You weren't breaking any rules, just doing what other people wouldn't.
Well, if we're going with Yiddish slang, the term would be freier, meaning "sucker" (https://www.haaretz.com/.premium-word-of-the-day-freier-1.52...).