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