First of all, your snake is not going to starve that quickly. If she is skinny/under fed obviously she has less reserves, but even still, they are built to go long periods without eating and their metabolism in between meals is very low. Not eating while she adjusts is probably more stressful for you than for her.

Your temperatures sound a bit on the low side, but your humidity is fine. Insulating the tank on three sides with cardboard, foam, whatever, will probably help and will make her feel more secure, too.

If she was in a rack before and now she's in a tank, that could be one reason she's having a hard time adjusting. There is basically nothing in her environment that is the least bit familiar to her, at all. When I add so much as one new hide, my ball python will barely go near it for days or even a few weeks; it takes ages before he'll actually go into it. And that's when everything else doesn't change!
And in a rack, she has probably never had so much chance to see the world outside her enclosure through the glass, either. So there's just a TON of new stimuli.
If you know what kind of bowl, hide, substrate, etc, she had at her old home, you can try giving her those (in addition to what she has now - it's pretty hard to clutter up a BP cage too much) even if you plan on changing them later. You can also cover the front of the tank with cardboard so she can't see out. You don't have to leave it that way forever, just until she's more used to her new environment.

And especially make sure the tank is covered and she can't see you when you're feeding her. You can still peek around the edges. But a BP is pretty vulnerable when it's eating, so if it thinks any potential predators are watching, it won't eat. Some snakes prefer to be left alone in the dark with their food; with others that won't work because they only register it as food if it is 100 degrees and moving, so you pretty much have to warm it and then wiggle it o the end of tongs.

There's lots of good info on this site; just be patient and don't freak out.