I don't worry about the eye level thing. When a child sits in the room and looks around they notice the floor, the ceiling, the shelves, walls etc and they will see the work and appreciate that it is where no one can rip it. I have some shelves that are 24 inches deep they kids have toys on and I put seasonal pictures, etc. on those walls which they can stand and look at but not reach.

One option if you want a child level display is to get a piece of plexiglass so it is unbreakable and then use mirror clips to put it in place, you would remove the glass, post the pictures and then cover in the plexiglass. The mirror clips screw into the wall and you can get it all at any hardware store.