Madison would have less regard for Trump. The mogul's campaign is half populist crusade, half insult-comic shtick, but Madison thought that one virtue of representative government was its ability to elevate the political discourse. In Federalist 10 he writes that our system can "refine and enlarge the public views, by passing them through the medium of a chosen body of citizens, whose wisdom may best discern the true interest of their country, and whose patriotism and love of justice will be least likely to sacrifice it to temporary or partial considerations." Trump is the antithesis of these ideal statesmen the Framers hoped would staff the government. Madison himself notes that "enlightened statesmen will not always be at the helm," but this is hardly reason to select as president somebody as benighted as Trump.
Madison would, moreover, likely be unimpressed by Trump's wealth. In the 1780s and '90s, speculative activity had reached a frenzied state, and many a man had amassed himself a large fortune. Madison thought that this demonstrated neither virtue nor industry. In a debate at the Constitutional Convention over whether certain offices should require their holders own property, Madison argued that holding property was "no certain evidence of real wealth. Many enjoyed them to a great extent who were more in debt than they were worth. The unjust laws of the States had proceeded more from this class of men, than any others. It had often happened that men who had acquired landed property on credit, got into the Legislatures with a view of promoting an unjust protection (against) their Creditors." What might Madison think of the "real wealth" of Trump, who inherited a fortune from his father and whose companies have had to declare multiple bankruptcies?
Madison would appreciate how aggravated voters are—in the 1790s, he himself felt like the government was being hijacked by an interested faction—but he would never support for president a meanspirited, inexperienced demagogue such as Donald Trump.