At 5 months, my general rule of thumb was not to feed more often at night than during the day. So, if she can go 4 hours during the day, she can go 4 hours at night. We do a df, so for us, it ends up looking like df around 11, nf around 3, wake up time around 7-8 (sometimes I actually get an extra hour in there!). If she's taking in so many calories during the night, she probably isn't interested during the day.
Is she a 2-sided feeder or one? With the girls, I used to be able to get away with only feeding from one side if they woke at night -- or would try to get by with a small feed. You could also go the pu/pd route, not sure how you feel about that....and remind me, does she have reflux? PU/PD and reflux don't work so well together. Any luck resettling her any other way? Sometimes with James, I find that it's much easier to settle him in his crib, as if I take him out, he's immediately thinking he's going to get fed.
What's her day sleep looking like? Do you think it's just hunger that's waking her at night or is she waking for some other reason and needs to nurse to go back to sleep?