I’d offer this scenario.
Probably in the range of a dozen states to attempt this, prior to the primary....likely giving ‘bonus-points’ to DeSantis, and the states involved would likely sue red-states to ‘cooperate’.
But this invites the scenario....if you were a Trump-voter in the primary and can’t vote for him....do you ‘write-in’ (trusting the system) or do you register as a Democrat to vote for RFK instead...causing even more chaos?
These are all questions that you might ask in the 1859-state-of-mind.
Exactly how does one write-in a candidate’s name on a preprinted ballot which will be run through a computerized Dominion voting machine?