I'm sure most of you know this, but this is called a "faithless elector." It's not that uncommon (in the past 16 elections, eight have had one, nine if you count one in Minnesota who misspelled a name on her ballot), but only one elector has ever been faithless in any of those elections.
Not only that, but 1) about half of the states of the Union have laws against faithless electors (including most of the crucial swing states), 2) even if there isn't a law against them, the electors are usually party loyalists who are impervious to lobbying, and 3) even if they weren't bound for Trump, they wouldn't be bound to vote for Clinton, either; in fact, every faithless elector has either been for a third-party candidate, a non-candidate, or a blank vote—never for the other major party candidate.
Believe us, trying to stop Trump from getting office using bureaucratic tricks isn't going to work. Ask the Cruz/Free the Delegates campaign.