I had a thought or two on this so lemme butt in.

Go to the junkyard, bring your tape measure, and find a door the same size as the one on the room.
Pay particular attention to the hinge placement if you are not up to moving them.
If the existing door is a standard size, it will at least be close.
Pull the hinge pins and store the landlords door so you can replace it when you move out.
Under a bed comes to mind, but wrapped in plastic, they make excellent plant tables.

Install your "junk" door and cut holes in it one at the top, one at the bottom.
If you put an intake fan, with a filter and light baffle in the bottom hole, the hot air will be ported out the top.
That will also allow you to use a "cool tube" for the HPS and port it out the top hole with some "dryer duct".

If none of that works for you, you can try relocating the ballast to outside the room.
Just extend the wires that go to the lamp.
Ballasts run pretty hot and that should help a little.


I hear you about the damn street lights
If you have a light meter, go out on the patio and actually measure the illumination.
Anything under 1 Lux will not affect cannabis.

Aloha,
Weezard