you will need 2 different thrmos for this rack. i made one like this and quickly ditched it for a rack for the smaller tubs and made cages for the larger animals.

i had 1 pannel of 11" flexwatt for each of the 41qts and it got to the correct temps.

this style rack will work but i had some issues with the cold side being too cold. and when pulling out the tubs, they tend to tip if any weight is towards the end you are pulling. good luck with this!! i hope it works out for you.