My idea is to take a rural county with a population of 40,000 people or so in a state like Pennsylvania or Wisconsin ... and during the next statewide election in that state, have 500,000 ballots show up for the Republican candidate from voters who are suddenly registered to vote there. Have them registered as homeless people living on streets or in state parks and campgrounds, if necessary -- all legally, of course.
You'll see the tightest ballot security measures in the western world imposed after that.