These are good questions you raise.
As far as determining how to identify Trump refusers, I suppose one could cross reference census tracts and compare Republican party membership with voting results, but I guess that would only provide rather broad brush data. I suppose the most effective method would have to be a questionnaire that party members would be obligated to complete and answer truthfully. Those who refused to support Trump even though he was the party’s nominee would be stripped of party membership.
As far as additional consequences, I think banishment from Republican Party social events and gatherings would be a good start, along with publishing their names on a list which could be distributed to their neighbors. I can probably think of more, but these are the first two that come to mind.
Those methods would probably out most, but you might also want to interview the neighbors and coworkers to find out if they ever uttered any phrases that might be critical of Trump. Also, promise children rewards if they alert party officials to anti-trump statements they overhear in the home.
“...These are good questions you raise. As far as determining how to identify Trump refusers...”
You are actually *serious*? Sending folks to the political Gulags for disagreeing with you? You represent Trump perfectly! You seem to be “kindred souls”.