My end goal would be to have them separated. I don't see the issue with housing them like this temporarily but I think the hide situation could be better.
Yes, at some point the two will try to breed.
As for being in a cage that is to big, it can be done if done correctly. I have raised my BP in a 40 gallon by giving nice hides, real and fake plants, driftwood, vines, and moss. All of these things make the snake feel secure because it can move around the large tank feeling secure because it has cover and concealment. The key to housing a snake in a tank that is to big is filling it will things that make the snake feel secure.