I am looking to purchase an amplifier for my 2005 Seedoo Speedster 200. I actually bought a cheap 4-chan 1200W amplifer and 10" sub from O'Reilys. This was a quick fix purchase in preparation for our community's boat parade. None of this is marine grade. I actually already ran the power wires (both gnd and pos) from the battery to the glove box (had to pull the cupholders and use a wire fish tape). This worked great for the event, but my battery was dead the next day (deep cycle). I plan to move the O'Reily stuff to my truck and want to replace it with a properly powered amp.

What is a good amp suggestion? JL, wetsounds, clarion, polk?
Also a subwoofer? Should I cut or should I just get an enclosure and find a place for it.
Should I add an isolator, second battery, tray on other side?

Also, in case anyone is interested, here is a video of my boat for the parade: