I'm not an expert of swing/fling states, but FiveThirtyEight listed 22 states as potentially competitive; Trump also won 194 of the 207 counties that voted for Obama either in 2008 or 2012; and finally I count 8 states that shifted to Trump after voting Obama [1]. Therefore all hands are required to win an election, even for the first 49.9%, even if a few fling states make the difference at the end.
Of course, although it's not possible to earn an election purely by fraud, it could still alter it.
Wisconsin was not considered to be a battleground state. HRC didn't even campaign in the state after the convention.