I would combine RaceR86's HX-1175b and Jerommel's 2S2P ideas. Use 1206 sized resistors if you change the current. The heat seems to be comming from the voltage sense resistors. I think 12 amps and beyond is fine if you pot. Here's an easy, reversible, and cheap potting recipe.
Keep in mind that I switched the FET's out on my HX-1175b. Not sure if it is critical to keeping the heat down at 12 amps or not. Relic reported the stock FET's get hot. Comfy's FET's don't.