Imo, pretty much all third party candidates are doomed to lose, no matter who they are, unless they have explicit backing of one of the two major parties.

The best thing to do is change the rules before you try to play by them. This means attacking the 2 party system by the actual weak link: the first past the post voting system. Run on and vote in candidates to the two parties who vow to dismantle it. Elections are run by the locally, so we can do this state by state, city by city. This is achievable and has already started in some cities.