Sounds good, one thing i didnt hear about was a fuse. (1) for the main power cable and (1) for each amp at your distribution block, the four gauge should be enough to power those two amps. When wiring your ground should be as short as possible, just keep the power and grond away from your rca cables. make sure your amps will stay cool or the thermal switches will shut them off, we tapped into the blower motor on my buddys boat to vent cool air over them, mounting the sub underneath the deck might make it skip if it hits hard enough, your battrys should be fine ive been running that type of setup in my Suburban for a long time with great results