I recently moved and the apartment I live in now is a bit cooler than I'd like.

I have a 20gal long Critter Keeper with screen top on a stand with a wooden canopy above. I have a UltraTherm under the tank heater which keeps the ambient temps inside to about 80-84 (depending on the ambient temp of my apt) for my Hog Island boa constrictor I'd like to increase the temps a bit. I believe it's just a bit too chilly in there at times for her based on her behavior, though she seems to digest food just fine.

I'm thinking of getting a radiant heat panel and mounting it above the tank over where the UTH is located. The distance between the screen top and the wooden canopy where I could mount the radiant heat panel is 7".

1. Would I be able to increase the temps with a radiant heat panel mounted onto the canopy?

2. What size radiant panel should I get to increase the temps to 84-86F?

3 Three hat vendor would people recommend (I've know of two) ?

4 Would I need a thermostat, like a Helix or something similar??

I'd appreciate any thoughts- w/the the exception of getting a new set up. I don't have the space for a new set up.
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Pie-Bald Ball python
Hogg Island Boa Constrictor
Woma Python
Several species of tarantula