Stereo battery issue 4 6V T 105's

After much research I decided to go with 4 6V Trojan T105's for my stereo bank (separate from alternator or boat batteries). I thought this would be more then enough juice to play my system loudly while floating/partying for at least 5-6 hours.

I finished installing all my system to find out the volts drop to about 10.3 when my bass hits hard and my sub amp cuts out.

Can someone please give me some suggestions on what I should do now? My alternator is a 90amp running to 2 blue tops for staring and back up battery’s.

My system consists of:
JL 1000/1 to 2 12W7's
JL 300/4 to 4 Polk Momo 6x9's (tower)
JL 450/4 to 6 6.5's (boat)

Thanks for any and all help.