hifonics are stout and cheap. I just put the ZX8000 five channel in my boat, running the sub and the boat speakers. You could use that one and have two channels running two pairs of boat speakers paralleled, 110 @ 2 ohm and the mono sub channel running one or two subs 300 watts down to 2 ohm, then you'd still have two 110 @ 2 ohm channels that you could run tower speakers off of or more boat speakers, whatever. These amps put out what they say they will, I haven't run mine wide open for an extended period yet, but at half volume it barely gets warm.
It would be wise to add another battery and a relay, switch or isolator. Just for peace of mind.
definitely not white chocolate caliber, but some of us can only afford snickers, they're pretty good too