My last RV a 40' Motorhome had a two ton heat pump which would keep the huge windowed coach at 75 in 105 degree heat in NM and AZ in the summer with the window shades open. This Montana has supposedly better insulation and more BTU cooling capacity but is not working right with all window blinds drawn. I did smoke test the MH and sealed many holes to the basement to get it so good. I suspect I will have to find a way to test air leakage of the HC 375FL if I ever get the cooling system running correctly. Ie. fix the airflow issue with the vents and ducts. 650 cfm in a space this small should make it drafty but mine is not.
BTW I grew up and still have family in Akron Oh and when I visit do miss seeing the Sun but it is similar in Frankenmuth Mi where I am for now. It would have been great if you knew the main slide roof temp before and after you did the slide cover.