Its not constitutional. The requirements for Presidents are listed in the Constitution. To do this, it has to be passed as a constitutional amendment by both houses of Congress and ratified by 3/4 of the states.
I wasn’t aware there were any requirements for president listed in the constitution.
No Person except a natural born Citizen, or a Citizen of the United States, at the time of the Adoption of this Constitution, shall be eligible to the Office of President; neither shall any person be eligible to that Office who shall not have attained to the Age of thirty five Years, and been fourteen Years a Resident within the United States.
I believe you are confusing requirements to run for office with the eligibility to run for office. People who want to run for office are required to disclose the source of all campaign funds among other things.
I have no issue with seeing somebody’s tax return who wants to be president.