Small correction, 150A through 0.1mOhm is 2.25W because P=R*I^2 but I'm guessing that was a typo.

So what you're saying is, you've been working for at least two months (or ten, somewhere in there) to design a VRM that isn't as good, to push power through traces that aren't as good. When did y'all find out you needed to be able to source 180A at 0.6V? Because that would have been a pretty good time to design the PCB with heavier traces.