Tell you friend to get an appropriate size crate. Get the dog used to the crate as it's own space. Gradually increase the time the dog spends in the crate and when the dog starts to act like it might need to go then take it outside. The dog will not mess in the area it considers it's bed/shelter.
Contrary to popular belief, it is not cruel to crate train a dog. The dog will actually claim the crate as it's own. We have 5 dogs and it has worked great for each one.
Hope that helps.
You are so correct. My 19 month old Golden Retriever even relaxes in his childhood crate. We bought the largest size to allow for this opportunity. The gate has been removed and he sleeps in there every night. He knows it as his space - exclusively. His housebreaking was effortless.