There are several flaws in your case, the basic one being that it only works if those involved want a Democrat in the White House. Without this, you are talking about people who want to circle the wagons, not run a circular firing squad. And you don’t have that.
Then you have the problem that Pence is just an average sort or Republican. Unless you just say that being a Republican is an impeachable offense, Pence is just not impeachable.
And no, these people are not at all ignorant of each other. They talk on a daily basis.
Your plan just won’t work unless the Trump situation gets so bad that you don’t want to try it because running against Trump will get a lot more votes than running against any replacement.