. Are there people who are saying they won’t vote for Trump publicly but who will do it when inside the voting booth?
I would say, yes. I don’t know for sure about what they are saying to the polls, but public support is much smaller than private support.
I live in the most conservative county in California. It votes for the GOP at a rate of 70%, typically. And there are a high percentage of Libertarians here.
Bush stickers and signs were all over the place, even in 2004. Lots of McCain/Palin, plenty of Romney/Ryan.
There is just nothing around. I see a handful of Trump signs. A couple of bumper stickers. No sign of Hillary, either. By far the most common political sign out now is the State of Jefferson stuff (There has been a Libertarian group trying to split off from California for decades, and it has risen much higher in visibility the past 3 or 4 years).
So I surmise that a lot of Trump supporters are smart enough to know what supporters of Trump look like, and they don’t want to look like that. A lot of people are smart enough to keep their bigotries to themselves except in the company of other known bigots. I am certain lots of people who are going to vote for Trump are hiding behind the Undecided or Gary Johnson camps at the water cooler, but will punch the ticket for Trump once behind the curtain.