Copper thickness for server PSU breakout

[Elphamyto]

Will a 2oz copper pcb be enough for a PSU breakout (~1200-1500W)? The two things making this difficult for me to calculate: I'm not sure what an acceptable temp rise would be, and I'm using copper polygon pours (rather than traces) for 12v and GND. Anyone with knowledge able to provide some feedback? Thanks in advance