I have 8 50 W Seelights run in parallel with 10 ga wire to a battery. Never an issue except battery dies around 4-5 hours in.
I have a similar setup with 8 50 watt and 2 27 watt. I split this system with two 14 gauge wires but they run off of one 12 volt. I get about 4.5 hours off of one 29 series, 12 volt battery.