With a 30 amp 220 volt feed you will have two legs of 110 with 30 amps each. That’s not much. Can you tap the panel that feeds the RV power receptacle? Barring that, can you add a 50 amp RV power receptacle?

I'm working on wiring up a bunkhouse (10'x20') for a hunting cabin. There are already 30amp RV plugs in place. My question is, if I wire the interior of the building with a sub-panel for a 10 or so outlets and 3 overhead lights can I then take a standard 30amp RV extension cord, cut the female end off and wire that into my panel inside the bunkhouse and just plug right into the RV plug for power in the bunkhouse? Seems like that would be a simple solution to getting power run into my sub-panel in the bunkhouse. What am I overlooking? Is this a patently bad idea? Only thing that MIGHT get left running power while we are away would be a standard fridge.

With a 30 amp 220 volt feed you will have two legs of 110 with 30 amps each. That’s not much. Can you tap the panel that feeds the RV power receptacle? Barring that, can you add a 50 amp RV power receptacle?

If you can get a 50 amp RV circuit installed that will do it just fine. But instead of installing a plug? Install a rain tight box and wire both ends directly (no connectors).

Appreciate the input from all. Plan to be down to get things wired up soon and will try to remember to report back what I wind up doing. Going to have an electrician give a final seal of approval on the setup even if it is just a video review. Sounds like I've got a couple of different options of good ways to run it that would work. Just need to see which will apply to the existing setup with the least adjustment and best supply of power.

Got most of the electrical roughed in. Ran 3 LED overhead lights, and 7 outlet receptacles. Plan to run a window AC unit inside, lights and small fridge. Outlets are on one branch circuit. Lights and fridge on one branch and then a dedicated circuit just for the AC. That is going to be the most power hungry. Calculated it up and there should be plenty of power. The branch circuit I'm pulling off of is a 70amp circuit. If I need to up grade the service inside my cabin I will be able to either tie the line direct into the 70 amp service or upgrade to a 50amp RV outlet. The plugs inside will be used for things like charging phones and computers. Don't expect they will get much use beyond that. No stove and not likely to use a microwave.

For hot water I plan to use a propane fired water heater. Runs off a standard 20lb BBQ tank. Worth looking into Simple Searcher. They run about 2-300 bucks and will give you plenty of hot water for a shower or cleaning dishes. I plan to set that up to be easily removed to store inside when not in use. Probably be working on getting setup finalized in the cabin for several more trips down.