That's actually six total girls, which is a challenge.
The City of Denver prohibits more than 3 unrelated adults in one dwelling unit. It turns out that the Supreme Court has ruled that law unconstitutional, but it's still on the books.
On the other hand, the only way to get caught is for an annoyed neighbor to complain. If there are six cars, that might annoy the neighbors.
6 x $250 = $1500 is a realistic price, but most landlords won't go for the six people.
Padmapper.com is the quick way to search Craigslist, which is where 90% of the fresh listings are.