I also have a 2 Story house in Dallas with a twist. It has 3 basically seperate attics. 1 over the bedrooms which are in a 2 downstairs, 2 upstairs config.
2nd attic is over the "no upstairs" portion of the home where the kitchen & dining rooms + garage are located.
Between these 2 attics is a sloped ceiling (goes from 20' to 24') that has perhaps 12" of space between the ceiling & roof. Unaccessible to man due to these limitations. I would est. this section is 42' X 27'.
This house has recently been re-roofed & now features ridge vents & new intake soffits. Insulation is original 1965 & minimal at best.
Question is how best to deal with this 12" portion that you cannot possibly crawl in?
You may be able to drill aprox 2" holes in the drywall celing every 2 to 4ft and blow in insulation. Unless this is a designed pathway for air to flow from one attic up and out the other. Then you won want to compleatly block the joist spaces up. Just an idea I am not a insulation person.