Battery recommendations for 1500W inverter

To the OP I just completed an install like you were asking. I have 2 Lifeline GPL-4CT 6 volt batteries. I installed a gopower 1500 watt pure sine wave inverter . The cables were 1/0 for all my cables. A total length of the positive cable was 1ft from battery to the fuse and 3ft to the inverter r. I have some done some minimum testing with a microwave just testing a cup of water for about 5 minutes in 1 minute intervals. I can’t remember my microwave size. I have a 2012 lance 855s. If I remember correctly the voltage dropped to about 11.5 when using the microwave. I hope this helps. I won’t be able to do any further testing for a while.