G Pope,
I would have to agree with you, it's all about the science (I think) 

  I'm getting ready to put the tank back into my square top and I have about a 2.5 inch gap to fill with insulation.  I bought the solid pink sheets from HD and the R value is 5 for 1 inch.  I'm going to glue the sheets together and go for it.  Besides, it's not as itchy....
SGM