Iíve cured porpoising on two boats with trim tabs. On one boat I installed powered tabs and on the other fixed tabs. I think it was a matter of getting more lift
aft to compensate for heavy engines.
The fixed tabs ended up just extending the bottom further aft. They had no angle to them.
They also made it much easier to get on a plane without moving a lot of weight forward.
I imagine engine fins like the Dolfin would accomplish the same thing.