Broadband bass traps are the way to go
So that standing cabinet is impeding the development of the room
- it is where the bass trap should go and the corner it is trying to treat is compromised by the cabinet remaining
Your listening position is undefined
- distance from the wall you face and distance in from the side wall would be helpful
- usually 1/3 the length of the long wall in
Distance between speakers are going to be an issue but they should be on the short wall and facing in at 60[SUP]o[/SUP] to focus at your listening position
Roof - only thing that I would do is put a layer of spray foam or other foam (diffusers) to cover the joins in the floor boards above
First reflection points are determined by the direction your monitors face
Take a ball of string, tack it down to your monitors (with blu-tac or similar) so that it is directly and centrally above the center cone of each driver, extend the string out as far it goes until it reaches a wall this is the central position of your first reflection panel on each wall. You can continue to work the string ray around the room to find 2nd and 3rd points of reflection but ensure that the angle of reflection is the same as the angle of incidence (should be 60[SUP]o[/SUP] or a total of 120[SUP]o[/SUP])
thanks for the offer of a meal, but it would be a hellavu trip to site and eat it with you.......