on my boat, I have:

cockpit 4 - Polk/MOMO MMC650 speakers

Sub 1 - POLK / MOMO MM2104 SVC

head unit is... Clarion CMD5

I would like to add 2 more Polk/MOMO MMC650 speakers on swim platform
on separate channel to use the fader on the head unit to turn these on when we are in the water.

I have a chance to buy these amps from an acquaintance c400.4,c300.2,c500.1

What amp or amps should I get and how should I wire them?
thanks in advance!