Yeah it depends on the rules and how nosy the RA is.
I used to smoke with no problems back in the dorm.
All I did was keep the window open and towel under the door. Stuck my head out and blew the smoke.
Febreeze sometimes, not always.
Easy.

Oh, and yes blunts and joints are damn near impossible lol!
There was a normal smoking session and it stunk for hours.

The hitters are the ones you need.
I used to use a one hitter pipe and my roommate couldn't even smell it, yet I used to smoke like this everyday. His room was only a foot away from mine.

HOWEVER:
This method is only good if you don't want your ROOMMATES to smell anything.
I bet your roommates are chill as you mentioned and your only problem is the hallway stinking up. Well, it's real easy, just close all doors with a towel under it and the RA won't smell anything. As for the RA coming to your door for whatever reason, meh they'll be chill. The rule is AS LONG AS THEY DON'T SEE IT. Even if they smell it they can't do shit but that's just how it is here. Dunno bout your dorm rules. They WILL knock which will give you time to put away the shit.

Next door on the same floor these people kept smoking without bothering to close the door or ANYTHING! The hallway stunk of weed half the time lol! Yet the RA never did anything.

As for your stash, I used to hide it in my drawer and only a day or two later would the sun dry it out LOL!!
Some dudes I know hid their pipes in their computers.
Don't gotta be too clever cause it just needs to be outta sight for the RA is all. But I guess it's important to be clever if you go to a dorm with lots of thieves roaming about. I went to a chill upper middle class school so there were ZERO thieves. You could leave shit right out and nothing happens. The ONLY thing that ever gets stolen was food lol.

Know what these dormmates i know did? They literally used duct tape over their entire door (like around the gaps/sides to cover any air leak) and had a window fan and a doob tube. Quite insane though, that's the kinda method you would use to hide smoke from your parents if they were in the very next room of a 2 room studio apartment you and them were in or something. They were uptight emos anyway. They still had facinating methods though, gotta give em that. Just that it's too obvious to have duct tape around the air leaks of your door.
But wow, you could stand right outside their door while they toke a blunt and not smell anything! Really did happen. But it sucks when you're not allowed out of the room which causes the smell to leak. They get mad paranoid too lol everytime I kept returning they thought i was the RA.
fuckin emos.