Looking at the pic, I think Banana will be just fine. Just a few changes that I can recommend (I had a bp that fasted for 6 weeks, just started eating last month).

1.) 30L is big enough for your snake. I'm guessing that's what you have - not the 30 gallon one for fish which are usually taller with a smaller floor area than a 30L for reptiles. No need to up the size.
2.) Replace the temp/humidity gauges with a digital one with probe like the Acu-Rite Indoor/Outdoor Thermometer/Hygrometer/Clock with probe. You can get this from Wal-mart for 12 bucks. Put the probe under the warm-side hide. Since you got your heater on the side of the tank, you might not be capturing the actual temperature where Banana is usually resting in. Put the Acu-Rite unit on the middle of the back wall, as close to the floor as you can. Now, your inside temps reading should be around 80-85 and your outside temps reading should be around 90-95. And the humidity should be around 50%.
3.) Offer food every week. If she eats, cool! If she doesn't, then don't worry much about it, just offer it again the next week. Are you feeding f/t? You can refreeze the food once but after that, you'll have to throw it away.

That's all I got.