A lot of eminent domain will be needed to build that wall. Deal with it.
First, a border wall is a public use. No problem with using eminent domain for that. It’s Trump’s support for using it to transfer property into the hands of private developers that is the problem.
Second, if you believe that Donald Trump—the guy who called Mitt f’ing Romney’s immigration plan “too harsh”—will actually build the wall he’s talking about, well, I’ve got a bridge to sell you. He’s a huckster, who says things that people want to hear.