How to make BP more secure? And other questions!!

I have my 550g BP in a 35G tank. On the back and sides I have covered with black paper. But should I also cover the bottom third or so with black paper, so she feels more secure?

Also, I have two hides, a water dish and a fake plant. Would it benefit her in anyway to add a branch or another level somehow in her tank?

This tank is:
12" deep
~48" wide (i think)
~19" tall (I think)

I'm not too sure on the dimensions, I'm not at home right now. But it seems oddly tall and narrow, that's my only problem with it.

Thanks for your help!

See if you can stuff more stuff in her tank, like fake plants or whatever, and if you use a loose substrate like aspen or cypress, make little piles of it around the tank to take up some space, or if you use paper towel or newspaper you can crumple up some newspaper into balls and put them around the tank. You could also try adding another hide or something.