On Saturday, June 8, 2013 8:04:15 PM UTC-7, Craig R. wrote:
Not having studied thermal dynamics, etc, I have two rookie questions. How does the container material (thin plastic "milk jug" in freezer vs layered fiberglass for tail tank) and the shape of the container (minimal surface area of a milk jug vs long thin tail) effect these calculations? ... also, head space in jug is zip and in tail tank is large....

Having not studied thermodynamics you have saved yourself from a lifetime of boredom (even it if was only an hour a week). To a good approximation, the shape is accounted for in the surface to volume estimate, and the head space is not consequential to heat exchange.