I have some ideas:
1: between the end of the Civil War and the Panic of 1907, have several states of the Union declare through constititional ammendment the ownership of gold, silver, "and other precious metals and stones" to be a fundamental inalienable right, while at the same time denying those states the power to demonetize said materials.
2: D. C. Stephenson does not break with the original Klan organization, and insists on making sure that they stand for a platform, not a party. If he can manage to buy Valpariso, so much the better.
3: Without altering the outcome, or the substance of testimony under direct examination, make the trial of D. C. Stephenson look to all outsiders like a frameup and/or railroading. The Klan must be wounded, and not in charge during Black Tuesday, but it must remain organizationally intact so that it can capitalize it later at the polls.
4: Either Giuseppe Zangara succeeds in killing Franklin Delano Roosevelt, or if he must be elected, have the Business Plotters approach MacArthur, Stillwell, and Patton.
5: Huey Pierce Long needs a guardian angel.
6: Father Coughlin needs a ninja reputation watchdog and publicist.
7: Have news of Stalins Gulag reach the Wall Street Journal, while Henry Ford recapitalizes The American Mercury, with credible accounts of Soviet "Observers" of parts of the New Deal, making them more sinister than they actually are.
8: Spread rumors of Nazi infultration... of Boy Scouts of America. If possible, by adopting brimmed officer caps rather than red berets, Scots bonnets, kepis, or baceball caps as official headgear. Make mountains out of the molehills of Baldur von Schirach's American roots and annual vacations.
If you can combine at least five of those without forcing a move to Alien Space Bats, the fireworks will be awesome.