Side-mounted Flexwatt on CB70 rack; ways to bump up temperature? Is it necessary?

Hey everyone,

So a few months back, I came into possession of a CB70 rack (7 drawer) with side mounted flex watt. I used to have the rack in a spare bedroom in my house, but since then my sister has moved in and I can't keep the snakes in with her as they freak her out (wimp!). The room they were moved to has a lower ambient temperature. I have a thermostat hooked to my rack, but I basically have to let the flexwatt run unregulated to get an appropriate basking temperature on the drawers (ranging from 88-91 degrees on the sides of the drawer, near the heat tape, temperature depending on position in the rack as some run cooler than others). The cool side is roughly 75-78 degrees.

I've noticed that a few of my balls spend almost all of their time on the cool side, and when reading their temperatures, they're not usually warmer than 90 degrees on the warm side. However, some of my other balls spend almost all of their time on the hot side, with the same range in basking temperatures as stated above.

My question is, does anyone have any tips as to how to "insulate" the rack to keep the temperature better? Right now I have my thermostat set to 94 or 95 degrees to reach my 88-91 degree basking spot, and when I allow the tape to run un-regulated (no snakes in the rack at this point), the tape itself only seems to reach about 96 degree and it bumps my drawer temps up to about 93 degrees.

Thought I would ask if anyone else has encountered this issue and if there is any fix to it other than upping the ambient temperature of my house!

Thanks!
Kourtney