If you are concerned about it going rusty why not go and give it a clean & and oil? give it a wipe over with a oily rag should give it some protection, could do it weekly?
Then after a decent amount of time......6 months?...... since you have been caring and loving towards the frame, it will love you like a parent and then it will only be humane to bring it indoors.
I like that idea very much.
I might even do it.