Well, since Danielle Wilson sounds made up, we can as well pretend she was born in 1981 instead.
With a billionaire backing her campaign and several well-connected politicians in her team and a talented election campaign management, I think the best performance she could pull off would probably be something like Ross Perot in 1992. But you'd need a scenario where both Democratcs and Republicans have been going morally and politically bankrupt, i.e. a Watergate-esque thing happening in both parties. Given those kind of circumstances, people might go for a candidate only involved in local politics (therefore having more actual experience in politics than OTL Trump) and therefore not being corrupted by "the system".
But in reality, Trump wasn't really a dark horse: he was well-known throughout the USA and beyond, he already dabbled with the GOP nomination in 2012, he was involved in the Reform Party, and despite having no experience in politics, he always was well connected to the political machinery. In certain ways, Bernie Sanders was more of a dark horse than Trump - and Fiorina and Carson on the GOP side as well.