30 Amps to 20 Amps

We're visiting relatives in Washington State later this fall. They have 20 amp service available. The only thing we need to keep going might be the fridge, lights and possible TV from time to time. Is there an adapter available to take the 30 amp down to 20, similar to the one we have to step down 50 amps to 30? Might it be a good idea just to run the fridge on propane? [We're talking 3 days max.:confused:

Thanks in advance for you assistance.