If he finishes bottles, add an ounce to make them 5 ozs.
I think I would be tempted to try skipping the DF to see if that makes him wake for a single night feed a bit earlier in the night - offer a full 5ozs and see if he can then make it to his wake up time. If so, he just might take a full bottle at wakeup.
Give it a few days to see if it works... some babies just don't really do much better with a DF, so I would try going without.