Dividing a room in half without harming apartment walls?

Dividing a room in half without harming apartment walls?

With summer coming-- after all this snow melts, at least-- I've thought of something that might help with summer power bills if I do decide to use the AC. (Usually it's not too bad around here, but I'm on the top floor and it can get extremely hot and muggy.) I've just got a small thing I have to figure out. My apartment's AC unit is in the living/dining room of the apartment, diagrammed below in MS Paint. The black lines are walls, the brown and blue lines are doors, a sliding glass door that leads to a balcony, and windows, the purple blob is the AC unit, and the green lines are hypothetical partitions. The scale on this is a rough estimate, at best. My idea is to put curtains or something in the spaces indicated by the green lines, and primarily cooling the air within the living room proper. The curtain in the hall will be simple; I have a spare tension rod that should reach across the gap, and a spare light blanket to drape or hang from it. I've done that before elsewhere, and it works surprisingly well. The larger gap, between the living and dining rooms, will be harder. I'd estimate it to be between twelve and fifteen feet, and I doubt a tension rod would hold the weight of cloth heavy enough to block airflow. I'm not supposed to put holes in the walls, but I think I could cover up small ones well enough to pass inspection in such an odd position. I'm thinking that something like a tri-fold standing partition might be better, but also sort of awkward to get around to access the kitchen and dining room. Does anyone have any ideas for something relatively inexpensive I could cobble together in the next few months? (Admittedly, I am planning way ahead here.)
“Bats”!

“Bats”!

Let’s play everyone’s favorite game….

Let’s play everyone’s favorite game….

In my garden this morning

In my garden this morning

Raised Bed Garden!

Raised Bed Garden!

new apartment.

new apartment.

Dianthus

Dianthus