Lot and S'dom

We learned about the story of לוט and the city of סדם. He greets these visitors, and he pleads with them so they will come into his house. So then all of סדם comes to his house and bangs on the door looking for the 2 men (or angels). לוט comes out and says - "oh, my brothers don't do this evil, I have two daughters, you can take them but don't harm these men or they'll be judgement between us." So the men extended their arms, wanting to break the door, לוט saves the men and the people leave. אברהם looks towards Sdom and sees it in smoke - G-d remembers אברהם and sends לוט to him, לוט had sexual relations with his own two daughters in order to have עמון and מואב - because so many people had been destroyed.
So there are two interpretations of this story. One from רש''י and one from רמב''ן:
רש''י: Everything in this story is literal - it's מדה כנגד מדה: he, לוט, gives his daughters up, then he has sexual relations with them. This shows us how לוט and his tragic downfall was the complete antithesis of אברהם.
רמב''ן: The whole thing is more sarcastic and isn't meant to be taken literally. It doesn't make sense - why would 500 people come to rape two people? And why on earth would לוט be willing to give up his own two daughters? When they were banging on the door asking for the guests, it showed how inhospitable the people of סדם were, and when לוט offers his daughters he was speaking sarcastically to show the people how horrible their actions were. After this סדם was mad at לוט for rebuking them, which proves that סדם really needed to be destroyed.