I’m going to expand on an initial idea I successfully pulled off at an individual level for this election. I found a friend who was a fellow Florida voter and together we cancelled out our planned reluctant duopoly votes and both agreed to vote for a third party. Scaling this to actually affect the outcome requires national ballot access of some sort, but once we have ballot access and at least a pool of potential candidates, the plan can start working.
It starts with an initial pairing in the same winner-take-all state. This is a pair of two people who have reason to at least trust the other to keep their word, for whom backstabbing the other wouldn’t be worth the detriment to the relationship for a mere 1 vote advantage. Once paired, these two individuals each seek new pairings of their own, but don’t tell the other who it is. When both have found new pairs, their agreement is severed unless both become “stranded” by both of their pairings backing out, in which case they re-pair and attempt to start over. Of course in the long run this may help by starting a new branch, and a stranded individual can always start over by themselves.
This can scale exponentially, and since all connections go back and forth between parties, it becomes difficult for one side to follow the chain and stage a coordinated backstab. Plus, in each case, these would be personal connections which strengthens the accountability and likelihood people will keep their word to each other.
Additional payloads can be added, such as an agreement to make every effort to sign to give Unity ballot access or to participate in the nomination/voting process (so that most people are ok with the pair challenging the duopoly), and while it is vulnerable to offshoots and competition, that only makes election day become finally interesting.
Please try to break this (imagine how you would thwart it as whichever adversary) or improve it as best as you can.