Congratulations
You have just re-invented the "cargo hammock" or "storage hammock"
If you have a good Navy surplus store nearby, you can get commercially
made ones.  If not, you can get cheap "pickup truck cargo nets" in the 6 x
8 foot range.
Screw-eyes will work OK for hanging them, IFF the load isn't too heavy and
the overhedad supports are sturdy.
You could also consider putting in hooks, and hanging a piece of plywood
as an overhead hanging shelf.
Or extend the existing shelving higher and get a ladder.
--
Grumpy Ol' Fred        cisin(a)xenosoft.com
  My latest bright idea, an 8x10 net (maybe 10x12) to
hang from the garage
 ceiling to hold all my big empty boxes, bags of filler, etc. (a good
 portion of my garage has a 14' ceiling, so I have a lot of "room" even
 above head height. I'm am not entirely sure what one end will be anchored
 to, but I am so jazzed at the thought, that most likely I will run out
 first thing in the morning and buy and put up the net (anything netlike
 should be fine). Lets just say that right now my empty box and foam
 collection takes up about one 8x10 rooms worth of my garage and house.