Eating,lighting,humidity

My Ball is about 8 months old and is eating 1 medium to large feeder mouse every 5 days....sometimes he is showing signs of hunger 3 to 4 days after a meal. Is this too much? I feed him live when I put him in the box I feed him in then drop the mouse in it takes less than 30 seconds for him to take the mouse. I have a 20L tank and a 75w basking bulb temp is usually 85-90 during the day and I have a personal humidifier that I have rigged up that keeps the humidity about 75-85 is that too much/not enough?

I would lower the humidity a bit

What should I lower it too....and should I leave it there all day/night?

50-60%, 70ish for shedding time I believe.
As far as feeders go, most will say 10-15% of body weight of the snake (grab a digital scale that does grams), or the same girth as the largest part of the snake.
Up to 5-600g snake, every 5 days, over that every 7 days. (again, this is what I've read, and mostly based on opinion and the individual snake on when to switch up)

50-60% is fine, I raise the humidity higher by spraying the bin during shed