To answer the why not just use wire question: on a recently purchased cheap frame, I installed tiny eye bolts and wire like I've done many times in the past and a few days later I found the picture on the ground when an eye bolt pulled out of the substandard particle board frame.

Yep, and I agree that this thing is probably not even actually wood, but some sort of foam. I just ordered a 30" cleat from Amazon. I'll have to connect it at either side of the frame. I may drill a couple of extra holes so I can use 2 screws on each side, and then hopefully, it'll line up so I can mount to 2 studs.

I use these anchors all the time, if I can't hit a stud. They screw into the drywall, never a failure.
http://forums.pelicanparts.com/uploa...1482200938.jpg

Yep, I have some and love them. They make a big hole, but are worth it.

And about half the time when planning to use zipit fasteners - I end up locating at least 1 of them AT a stud!

You don't use the knock on the wall stud-finder test? Then if I'm close, I'll drill a tiny pilot to see if I strike wood.

Since we are talking studs, this is my favorite stud finder, use it almost daily. Basically a powerful magnet that sticks to the nail or screw: C.H. Hanson Magnetic Stud Finder-03040 - The Home Depot