flexwatt question

so this is going to be the 1st time im building a snake rack using 41qt tubs with 4" flexwatt for belly heat. my question is should i use double the flexwatt or will just 1 be sufficient?

One of my racks uses 32 qt tubs and 4 inch flexwatt and it works fine.

depends on the room air temp. If the room temp is the typical 80º there should be no issues.

even if i use it on the bottom across the end of the tub. and i will have my rack in my garage so the temp now adays is in the 80s