Advice on belly heat vs. back heat on racks

I kinda feel stupid for posting this lol

All the years I've kept snakes I never used rack systems. So I recently decided to go ahead and use a few to save some space. I've purchased totes awhile back playing with the idea of future racks, and the time has come to go forward with it.

I also learned that the businesses that manufacture the pvc racks do not make custom racks since I already have the totes. So I'm stuck making my own which is not a problem. The only issue I'm kinda stumped on is which heat would be better between belly or back.

I'm leaning to back heat since I'm using substrate in the bins. If I do it this way then the bins will be about 1 1/2 - 2" away from the back heat do to the handle and I'm not sure if that will any affect.

If I use belly heat, I'm not sure it would be able to simmer through the substrate.

I'm thinking of using 12" heat tape for the back heat and not sure what to use for belly.

I know alot of you have been using racks for along time and I would like to get advise.

You left a bunch of needed info out of the post.
What size tote?
What kind of animals?
Room temp and humidity?
Does the room temp and humidity fluctuate?

Sorry about that Gary

The totes are all 66qt
All my snakes are Rattle Snakes ( Crotalus and Sistrurus )
I keep the room between 75-80 degrees at all times and the humidity is 60% at all times
If there is a fluctuation it would be minimal.

I thought about maybe cutting off entire handle off of one side so it would be around 1/2 - 3/4" away from the heat tape. Not sure if that would be a good idea.

pygmies aren't bad in totes because normally they are hard to hook. A free air style rack with belly heat is your best bet. I would riddle your tubs with holes to allow proper airflow. I'm assuming you are choosing 66qt tubs because they are taller? I used 28qt in the past for same application.

I thought taller would be better when pulling the tubs out.
I thought about using 28qt tubs after getting used to the rack system and getting it honed.

So the heat tape will travel through the substrate using the belly heat method? I'm using 2 types, ground walnut for some and cypress for others.

What size heat tape should I use for belly heat and I assume it's best to have it in the rear of the rack.

Where should I locate the thermostat probe? The racks are going to be 5 tub.

I wouldn't use substrate for crotalus if your humidity is 60%. Un-printed newspaper is cheap and easy to use. The pygmies are different and I've kept them on paper and/or mulch with success. Yes heat will go through the substrate since you won't need much for them(pygmies). You probably can fill your need for a hot spot with 4" flexwatt. My 3x2 fb breeder tubs use 3" without issues. For these situations I like using the locking lid tubs so i can completely remove them from the rack rather than a slide out drawer situation. I put my probe on the tape and set my temps like that by trial and error. Other people put the probe in the tub and measure the ambient with it. Yes the heat goes at the back of the tub because normally its toward the wall where its cooler.

Well I have a general idea of how to do it now. I appreciate your time and advice, especially since you have a better understanding what I'm looking for since you have experience with what I have in my collection.

If I have any other questions, I'll PM you if you don't mind.