Congrats on the new BP
Some things:
40 gallon seems huge for a BP of her size, so I would recommend really cluttering it up for her so she feels secure and black out three sides with black construction paper. I always like to have BPs in tubs but if you're set on the 40 I'd do some cluttering for her to hide in. I also suggest having two identical hides for her (hot side and cold side).
You need your UTH (under tank heater) controlled by a thermostat. Without it being controlled it can seriously burn your snake. While you order a thermostat I'd either turn off the UTH completely or buy a $10 lamp dimmer from Home Depot and get it on there so it doesn't reach dangerous temps. The thermostats I use are ~$115 but I know someone has a link to a more affordable ~$30 one (can't remember the name of it).
Her hot side needs to be ~90-92, 76-78 is way too cold for her. Her cold side/ambient temps should be ~80. Her being too cold can cause regurges and other health issues. You need to know the temps, not guess. I use digital (Accurite) thermometers and a temp gun for direct hot side temps.
Work on your husbandry before messing with her would be my suggestion. There's a caresheet on here for BPs that I'd check out too, I'm sure someone will post a link if you can't find it.