There are people looking for anger — but the people who are going to be angry at Trump for paying little to no taxes are people who already are angry at Trump — so this would just be preaching to the choir. For Trump’s base, he would just spin it as “I’m smart, aren’t I? I managed to arrange things so that I could minimize my taxes. That gives him a pass with his base which is who you really want to affect.
Attack him for all of his failed business ventures. Everything that Trump touches fails. The only thing he consistently didn’t lose money on was his royalties from The Apprentice, and that’s because he wasn’t in charge of it. I’m pretty sure that that will put a dent in his followers, because one of their big pluses about him is
how he’s such a great businessman. Keep smacking him over the head for how he’s a failed businessman, until his base starts to have questions about him. Then you can use that as a bridgehead to question other things that he (falsely) crows about.