In looking at answering your question, I think you can't escape from secondary issues, being the sourcing and the translation. Because those are underlying assumptions of your question that make it difficult to answer.
those would be (1) that the story of Sodom and Gomorrah is, or is even intended as a literal historical account as opposed to a transcribed morality tale and (2) that the english version which references gang-rape is an accurate translation of the underlying hebrew stories.
First, most academic experts agree that the Hebrew Bible (i.e. the old testament) is a compilation of oral histories. See Schinderman How the Bible Became a Book: The Textualization of Ancient Israel (Cambridge University Press 2004) - you can read a briefer summary in this PBS article
So when things like the story of Sodom and Gomorrah appear in the Hebrew Bible, one of the first things you have to understand is that those are transcribed versions of oral histories told by the Israelite people. Oral histories can be extensive and detailed, but they are not in the same category as detailed written histories. The point is themes and morals. The morale of the story is about hospitality. Lot has a religious duty of hospitality to strangers. he honors his duty of hospitality at great cost to himself. he was a righteous man. The inhabitants of Sodom and Gomorrah were not hospitable people, in fact they were terrible and the opposite of hospitable, and they were destroyed.
Second, there is a substantial dispute among translators whether biblical account described in Genesis 19 actually describes rape. The hebrew word used is ידע "yada" (don't honestly know whether the pasted hebrew characters will transcribe). Some translators argue this word carries the cannotation of an "intimate" relationship, but only a minority of uses in the old testament use that word as a euphemism for sex. others argue the focus of the story is on inhospitability rather than an act.
To answer your question directly. The only references in "ancient" texts that I'm aware of also address the same story described in the bible. The events of Sodom and Gomorrah are back-referenced multiple occasions in the bible and are referenced in Rabbinic literature and also in the Quran. I'm not aware of any other independent ancient texts that describe strangers coming to a home and wanting to gang-rape newcomers to town for some reason.
However, if we look at the alternative interpretation that the primary focus of the story is about hospitality. There are ancient arabic/persian/indian folktales that likewise tell of various "bad things" happening to people that are inhospitable to strangers. Some of these can be traced to at least the 8-9th century baghdad, with earlier oral origins. See Van Gelder, G. J. (2000). God's Banquet: Food in Classical Arabic Literature. New York: Columbia University Press
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