Anyone breastfeed and use formula at night time to help keep baby full longer?! My daughter still…

Anyone breastfeed and use formula at night time to help keep baby full longer?! My daughter still wakes up every 2 hours or less (she's almost 9 months now) to nurse and refuses to drink milk if I put some rice cereal in it but I let her try formula once before and she had no issue with it and I heard formula fed babies sleep longer because it's more filling...I feel bad for doing it but this week I have 12 hour days coming up plus a 2 hour drive each way and I would really like to get more than a few hours of sleep.