The specific question was, "Is it ever okay to use two words, in to, instead of one word, into?" Because this is such a difficult topic, I'm just going to answer that question and not get too deeply into the differences between them.
Consider these sentences.
1. Without knocking, Edward rushed into the house.
2. Without knocking, Edward rushed in to to find Bella in Jacob's arms.
3. She ran back in to get her coat.
4. I turned the essay in to Mrs. Meents.
I think we can see in sentences 2, 3, and 4, it wouldn't really make sense to use into.
If it's followed by a verb, always use in to.
Mommy peeked in to see if the baby was sleeping. Here, "to" belongs with the verb "see."
Be careful if there is a possibility of confusion when talking about "turning into." Turning into the parking lot, shows directionality. Turning into a butterfly, shows transformation. Turning your homework in to your teacher does neither of those things. Consider these two sentences:
I turned the book in to the library.I turned in the book to the library.If you can separate in and to, it's clearly two words.
So to summarize, yes, you can and often should use "in to" instead of "into." Always use it before a verb. Also use it if you can separate the two words with the name of an item or person.
Harold went into the store. He went in to buy a grammar book. You don't have to go into the store. You can go go Amazon!
I hope that helps. I hope it makes a little sense. Let me know if you get it at all.