Heating different sized tubs

I recently tossed this rack unit together & had a question on how to heat different sized tubs while running it on a single thermostat.

I have ran a single piece of 4" flexwatt down the length of each self for the smaller tubs but, what should I do with the shelf with the 41qt tubs? I see people run the strips down one side, is it possible for me to do this & only use one thermostat? Or should I just run it the sameway the other shelves are? If I remember correctly you have to keep all the flexwatt the same size to use one thermostat.

http://i8.photobucket.com/albums/a49...1/IMAG2195.jpg
(and yes my wife has taken upon herself to use the extra shelves for a shoe rack for her & my daughter :rolleyes:)



Thanks as always!