When we were having such issues with Tucker we finally tried letting him sleep in the bed and guess what!?! No potty in the middle of the night and for our sanity no nasty crate and dirty dog to clean up in the morning! Maybe you could try that, then if he does have to go in the middle of the night you will be able to just scoop him up and rush him outside or do like we do and place him on the pee pad. I LOVE pee pads! My husband has to take our golden retriever outside to pee whether its freezing or blazing hot and when my yorkies have to pee they either walk to the pad on their own, or I place them there
Good luck!