So, I can't test this because my 6 is not hooked up to my phone line (otherwise I would). Before "closing as duplicate" know that this question DOES NOT ask "while I turned off cell data", so it's not a duplicate.
Cell data is on, but has no reception. Can we form a wifi hotspot still?
The reason being, apple does not give you access to high speed peer-to-peer. They indirectly do it through multipeer, and GK requires an internet connection so there's no real point in using it for p2p. Multipeer is slow, even for small text strings, huge (.33 seconds) lag.
So basically, no bars, data turned on, wifi hotspot work to form a local area network?