The problem would be finding a rubber band big enough to fit over your head that made a good seal around your neck. How did you find the right size rubber band.
I don't know how people manage to put their hands in handcuffs with a plastic bag on their head. How can they see what they're doing.
I agree. It sounds easy enough in theory, but when I actually tried to test the logistics of it, I had the same issues you mentioned and wound up seriously discouraged . Which ever you try to do first makes the other one way more difficult. How do you get the bag on and sealed if you're handcuffed? And if you put the bag on first, then you start panicking and losing breath before you even can attempt to try the handcuffs, which like you said is very hard to do anyway.
And I've never understood what kind of bag to use. The kind you mentioned that you get in stores, is that thick enough? If you use a garbage bag, do you use a very large one or a small one?