If you just want to have lights and keep the battery charged while storing then using adapters to get the 50 amp plug down to a 20 amp plug to connect to a standard house outlet is all you need. You can even run one A/C from a 20 amp outlet if you do not run much else. If you want to be able to use A/C and other appliances, maybe for use as a guest house for visitors, then you could get by with a 30 amp outlet and a 50 to 30 adapter. If you want full use of everything, then you should have a 50 amp outlet.
The links above by 2oldman provide all the info needed for wiring one.