I'm helping a friend build a cabin and we have a generator. I was wondering if I could wire an outlet on the outside of the cabin and another inside. The outside outlet would be for power in and the one inside for power back out, basically utilizing the two outlets as an "extension cable". Obviously we could just run a cable in the house but that doesn't look nearly as good. I'm also thinking of splitting off the wire and running a single light. Does this sounds plausible?
Yes, and I've done this myself.
But not two outlets. The generator side one is an inlet.
(These also come in a form-factor that is the same as an outlet).
From the inlet, you use in-the-wall wiring to go to as many outlets and lights as makes sense for a single circuit.
If you want 2 circuits, you can have 2 inlets, and plug each one into a different pole on the generator.
If you want >=2 circuits, you can have 1 inlet that is 20/30A 120/240V such as a NEMA 14-20 or 14-30, and then feed that into a service panel in the house. From there you can branch off as many circuits as you please!
PS. Once you get sick of hauling in fuel and maintaining the generator, look into solar+battery systems, and wire as many loads as possible to be able to work on low voltage DC. Lighting at the very least. LED lighting is your friend.