This is exactly how I've done it. It will stay there until you decide to take the block out. It takes a bit to find the right size of the wedge if you don't want wood sticking out of the back.
I use a couple pieces of thick folded cardboard to block my Floyd when changing strings (so I can take all the strings off and give the fretbaord a quick clean). Put one between the floyd and the top of the body and jam one or two between the block and the guitar body in the cavity. It works fine.