Search:

SoCal,
MAD777 is a minimalist (gram weenie).
His suggestion to make it wider means even more than mine.

Math is the same Width x Length x Heigh (See Catsplat spread sheet. Height of chamber is...

Temperature ratings are subjective, but I rely on this chart originally posted on HF.
1.5" loft = 40 degrees
2.0" loft = 30 degrees
2.5" loft = 20 degrees

For your dimensions 72" x 28" x 2" =...