What matters is the taxi, not the checkers. Stuff like tax returns is window dressing.
You can't turn corrupt officials into honest ones by changing the laws they're already turning a blind eye to. And you can't use systems (such as the political parties and their donors/owners) that exist to further corruption to reign it in.
Americans need to want honest governance, and be willing to go to the mat for it. Until and unless there's a substantial engaged minority will to do so, changing the rules is just theater. And if the government was honest, the existing laws are sufficient. Nothing stops Congress from removing Trump and the Supreme Court tomorrow, save their own lack of interest in doing so.
Personally, I think the best solution is to abandon the federal government as unfit for the purpose. Build a new one to handle what may actually be needed from the states and other existing and new interstate and international organizations. This will not be easy (gross understatement) but I think it is still more likely to succeed than any attempt to fix the current Constitutional government.