None of your options will accommodate adult females

Adult males can be house in 32 quarts tubs (23 1/2"L x 16 1/4"W x 6 3/8"H)

Adult females need to be house in 41 quarts tubs (33 1/2"L X 17 3/4"W X 6" H)

As for the heat belly heat is more efficient than back heat (back heat = heat loss).