quick question

I have an adult ball and a 3 month-old ball python, each in their own seperate terrariums with the usually setup... some cleaned small rocks, a artifical log, some fake jungle plant, some fake tree limbs to climb on, cypress mulch for betting, and approriate sized water dishes.

The adult stays in a 40gallon reptile tank, and the small, i beleive is a 25 or 30 gallon tank.

For the adult, I've been using a heatlamp on top of metal screen at one end of the cage with a 150watt cermaic bulb... average temp of 83f degrees using a ambient temp that uses two sensors at each of the cage, which also has a hygrometer, which usually states the humdity around 43%, though sometimes drops to 38%, though can spike higher when i spray the mulch and walls with some water upto 70%, usually back down to 40-50% within a couple of hours. The lamp is also connected to a reptitemp 500r thermostat, that lets me turn down the heat a bit at night to idle around 78-80f degrees.
the thermometer/hygrometer is a Zilla model with a LCD interface and two sensors for each end of the cage... I have one of these for each herp i own.

For the young ball, its basically has the same setup, though it has a 100watt lamp, and the ambient temperature from sensors setup at each end of the cage is usually around 80, somtimes ill through a another 60watt on top to bump it upto 84 degrees during the day. the hyrgometer reads about the same as the other, usually around the 40%-50% range. the lamp is also connected to a seperate repitemp 500r thermostat.

I'm thinking that the humitidy is far too low.

I previoulsy used sticky heatpads that were on the bottom of the tank, however, I always worried about the cypress mulch drying out and catching fire, and that it didnt quite seem to heat up the tank as much as the bulbs do... I'm not positive that ball pythons need so much of a basking spot as they do constant heat (as they are nocturnal... little hard to bask in the moonlight), but the heat pads did seem to keep the humidity in the high 50 to low 70 degree range. I also noticed the small one having shed problems, and while I've taken care of that by bathing it every other day, and having sufficient rugged objects for it to rub against in the cage, i belive its the low humidity affecting it.

I'm considering going back to heatpads, but I some questions on what wattages, size, and if i can place them on the side of the tank instead of the bottom, for worry of burning the snake and/or the mulch.

any advice would be most helpful!