I am really skeptical that 12VDC power distribution in RVs actually saves power compared to a high-quality (hah!) higher voltage AC or DC system. 12V is absurdly low and you can’t easily lose quite a few percent in resistive losses even with fairly large cables, and those large cables are quite unpleasant to work with and rather dangerous.

I tried using a microwave off the RV batteries, your inverter needs 4/0 cable. Very "fun".