I was thinking the other day that one of the differences between みたい and そう (meaning "it seems") is that the first can be bound to a sentence in the past while the second forces the verb of the sentence to be always in the ます stem. I think that difference allows みたい to create sentences like "昨日、雨が降ったみたいでした" meaning "yesterday it seemed like it had rained" (I don't know if the sentence or translation is right). Is that right?
Yes you can use みたい after the past tense of a verb, but the copula after みたい does not have to be in the past tense.
(Looking at the ground) It seems like it rained yesterday.
(Recalling the appearance of the ground I saw this morning) It seemed like it had rained yesterday.
(Looking at the sky) It seems like it's going to rain.
(Recalling the appearance of the sky I saw this morning) It seemed like it was going to to rain.
Note the difference of the time of your judgement ("seems" vs "seemed").