Good to know for these types of paintings. I do mine very similarly, but I like to display my paintings flat against the wall, when unframed, in a gallery setting. Therefore, I use eye-screws on the insides of the stretchers. This way, the painting can hang from two level drywall screws. This is the way most galleries prefer to display the work. However, once they are sold, they need to be wired for the buyer so that they have the option of hanging the work in their home from one hook.