The President has Twitter available to communicate to the people.
There are things he can do, and IMHO, should do, to get the press corps acting correctly.
One, eliminate all plumbing in the Press Room. The reporters can use the facilities at the Texaco station across the street if nature calls.
Second, Trump is the first president without dogs in the White House. This should change. If the President were to adopt 15 or 20 mutts from the local shelter, pit bulls, rotts, German police dogs, it could help keep these reporters in line. Using the Washington Post on the floor for the dogs to do their business would communicate a message to reporters about what he thinks of their paper.