These suggestions should really help your snake to settle down!!
If you don't like the idea of balled up newspaper in your tank, you could also go with getting some fake vines/plants to help fill in some of the empty space (it's also much prettier!!). This is what I did with my tank (as well as covering 3 sides) and my girl seemed to settle fairly quickly. I would suggest going to either a dollar store or a craft type store, or even Walmart to pick up some fake plants. Much cheaper than the petstores and it is all basically the same thing. I would just make sure that if you do get some fake plants, run your hand over all of it to make sure that there are no sharp points/wires sticking out that could potentially hurt your BP.
But I do agree that BP's settle much quicker in tubs than tanks. My new girl is set up in a nice comfy tub and it took her maybe a day or two to settle in her hide, where even with the vines and stuff it took my girl in the tank a couple more days to get fully settled. But that is only my very limited experience.