Fear of tearing the bag or removing it (while unconcious) is what got me looking into perhaps using a tent. There's also the slight claustrofobic feeling when pulling a small bag over your head, and the fear I might "roll out of bed" knocking over or loose my nitrogen tank. (everything will be secured in place/to the wall, but still, I tend to overthink everything)
The place I used to work at has these big inflatable plastic "sacs". I would call them bags, but they're really big. They're also made from a really sturdy material (plastic). I couldn't tear it with my fingers (nails), it's too thick for that.
The plan is to set up a camping tent in my room, put a nice comfy air matrass in there, and then inflating this sac with nitrogen inside the tent untill it fills the whole space (it's big enough for that). I currently got a 10L nitrogen tank which should give me about 7,000 liters (7 cubic meters) of nitrogen gas, which should be enough to fill the tent a couple times over if I'm not mistaken.
I'm not sure how I'm going to enter the sac/tent without all the Nitrogen escaping, and I haven't looked into how I'm going to disperse the CO2 once inside the tent, although it could be the volume of the tent is sufficient for it not to matter.
Prolly gonna make a stand-alone thread dealing with these things as I'm looking for input from more experienced members.