Unfortunately, the 12v circuit runs off the tiny accessory battery, which can't provide 1500W. I had trouble getting a 500W supply to work reliably. (Yes, the 12v battery is recharged from the HV 'traction' battery, but apparently that recharge circuit is less-than-1500W.)
Right now I've got a 300W inverter, and it works fine. I'd like to build it into the center console, so that I have a 120V outlet poking out the back. (Right below the rear-seat cup holders.) And it looks like Toyota Japan's website (sorry, I lost the link, it's in another thread on here somewhere,) they have an accessory 100V inverter that comes out the center support below the dash. IIRC, it's only 150W, though.
Oh, and I've thought about experimenting with a larger accessory battery (or even a second, more powerful battery,) to run an inverter off, but I don't know of the HV to 12v charging circuit could provide enough power.