Want to keep any Trump off the ballot? Pass a law requiring release of the last 5 years of taxes for any candidate for federal office. As a revenue-neutral bill it should not require more than a bare majority in either chamber.
If you can't get it through the federal legislature, you can still get it past several state houses, which control who can be listed on ballots -- including in Presidential races -- for that state.
The Republicans will go after it in the Supreme Court. But if it is a measure that applies to ALL candidates, the grounds on which to attack such a law is
[drum roll]
PRIVACY RIGHTS.
Which they've been arguing since Roe v. Wade DON'T EXIST IN THE CONSTITUTION.
[drum roll]
PRIVACY RIGHTS.
Which they've been arguing since Roe v. Wade DON'T EXIST IN THE CONSTITUTION.