You poor thing it's not easy is it.

DD2 has cluster feeds aswell but seems to change the time depending on the day, normally it's right as i'm doing tea, putting DD1 to bed etc...

How often does she feed during the day?
I only ask as when i was in hosp DD2 did it all night aswell, the MW told me the more feed she gets during the day the better she will sleep at night.
She was feeding 4-5hrly in hosp and then every 1-2hrs over night, i started waking her every 3hrs for feeds during the day and then just letting her go at night.

Trillians idea of feeding her before you go to bed works aswell, i no let DD go for feeds whenever she wants but have been waking her about 10pm for a feed before i go to bed and seem to get a bit longer out of her now.

During those night feeds is the room under soft light? i use a touch lamp in our room for night feeds to keep the room dimly lit as opposed to the nice bright lounge room during the day.

GL with it all, hope you find something that works for you.