A 220 lb hanger (including gear) would have to approach an support angle of 5 degrees to reach the ratings on these biners.
I figure my hang angle is never less than 20 degrees and that only puts about 1.5 kN on each support. (and I don't weigh 220 lbs with gear)
Wrapping it around a tree essentially halves that number.
4.9 kN rating should be fine for normal hanging.
Climbing gear such as the Nano are made to withstand shock from falls. Kinda overkill for us.
IANARP - WWYP
Oh, and I would pony up for a couple at least and probably 6.