one room recording/monitoring studio in nyc

I'm a long time lurker here, and finally committing to doing some room treatment to my 13' x 12.5' x 9'5" room. Any advice or ideas would be greatly appreciated. The photo attached is an illustrator sketch of the room, which is my living room/project studio. This is a rental, so while i love to build, i want to make as much of the treatment as possible removable. The majority of work done here is midi, but some acoustic recording is done, and i'd feel more confident doing more if the room sounded better. Basically, i'm attempting to simultaneously treat the room as a mixing/listening environment and recording area. If it weren't for certain details of the apt., i'd pack the corners with 703, build broadband absorptive panels behind the mix position and on the rear wall, and probably call it a day. The issues are - a) a steam pipe in one corner (red dot) b) a closet door which needs to open in another corner c) 2 floating shelves in a 3rd corner and close adjacent window d) no 4th corner (the gap is the wall closest to the hallway is an archway) I assume this last issue is sortof a good thing...no corner = no bass buildup. SO.. any ideas about ways to approach this room would be Greatly appreciated. I'm wondering, for instance, if the machine room/closet could be packed with 703 towards the wall side, and actually function as a bass trap/absorber? The walls are plaster and hollow, so i'm sure some low energy sound goes right through them?