I do something similar, but without the elaborate "tent" system.
I have 6" of foam underneath me. I sleep in a pretty thick sleeping bag (don't know its degree rating). Then I put a dense blanket on top. It is not super thick but looks like it is densely woven from cotton strings. It weighs the sleeping bag down well, and is easy to keep neat and tidy on top.
I arrange the top blanket to extend a bit farther up than the head end of the sleeping bag.
I will stick my head under all the covers so that my breath heats the space inside the sleeping bag and the humidity makes it feel warmer. Once I "run out of air" I tuck the sleeping bag under my chin, while keeping the woven blanket over my head. It allows just enough air to pass through to keep me from feeling as if I am suffocating, but still keeps my face warm.
I don't need any tent pole or wire or paper towel tube. None of that stuff would stay in place once I start rolling over in my sleep anyway.
I also sleep in a double-layer of sweat pants, a T-shirt, and an oversized hoodie. The hood keeps my head warm and face warm while keeping the blanket from laying directly on my eyelids.