If you can, route your wires from each of the power ports back to your 12V power center and hook into a known fuse. There's nothing worse than hooking into an unknown circuit, then popping the fuse to the fridge... or now you have no heat.
I added two power ports , one on each side to the rear storage compartments in our MH so I could run that 7 amp tire compressor. It would pop the 5A circuit breaker in the accessory panel (radio, powerport) on the passenger outside of the MH, and eventually the 7A fuse in it's own plug.
These powerports have dust covers, and are routed directly to the fuse panel to a circuit with very little load on it.
Sometimes finding a spot for power ports & the associated wiring can be a pain - but keep looking, you'll find something.