Anyone with a rockford amp will tell you they don't like low ohm loads. They're a regulated power supply amplifier, its going to attempt to put out rated power even if it doesnt have the power to produce it and that will kill it. You're going to be running a stock alternator, that is reason enough not to do it. Yes there are a few outliers but I wouldn't design a system around that, you wouldn't buy a yacht because you think you might win the lottery.