I haven’t got time to look up every liberal college. But I think that 4% number at Harvard supporting Trump, was a reflection of that particular candidate.
According to this 2015 article it’s not necessarily easy or fun to be a conservative at Harvard, but 12% or so of the population identifiy themselves as conservative or very conservative: http://www.thecrimson.com/article/2015/10/1/conservatives-scrutiny-oct-2015/ The Crimson’s 2012 poll shows 25% of Harvard students supporting Romney. http://www.thecrimson.com/article/2012/11/5/crimson-presidential-poll-2012/
I am not an admissions officer, but I know that the schools are looking for thoughtful students of all stripes. So unless you have truly offensive beliefs, and especially if you are involved in projects that are improving the lives of others, I don’t think being a conservative would be a problem.