Romney did not have the same luck with Obama.
Your analysis of the Libertarian vote does not apply to the 2016 election.
In 2016, the Libertarian candidate for president publicly campaigned for Open Borders and Amnesty.
In 2016, the Libertarian candidate for vice president publicly stated he would vote for Hillary Clinton if he was not on the Libertarian ticket.
Trump would have been lucky to get 50% of the Libertarian vote in 2016.
On the other hand, the always hard left Green Party had record turnout in Wisconsin in 2016, and their 31,000 votes would have won the state for Clinton.
If some visionary had advised the Green Party that Trump would win the election, 90% of them would have switched their vote to Clinton.
Didnt Wisconsin put in some kind of voter ID to reduce fraud as well ?