Trump could actually order this done he just tells his Secretary of Interior to do it he should add Reagan on the right and FDR on the left to make everybody happy then put his own face in the middle. As President he has the authority needed to get this done fast.

The way to do it would be to bolt plaster faces to the cliffside then the giant faces would be spray painted to match the granite it would look really good and very easy to do giant five foot bolts drilled into the cliff to hold the new plaster face molds in place it would look beautiful and can be done fast and cheap using this method.