I do not know if this really is a big problem and havn't really experimented with it that much but i found out that you can with atleast the stone edge have signs with no stuff in them that will stay there.
If you are fast enough you can move away like the same second you build it and then you got a sign that doesn't have stuff in it that is there and it got hitbox and all that and if you want you can right click it and fill stuff in but it will go away if you leave nothing in.