How can I convert an exterior light junction box to an exterior duplex outlet?
Do you have room to install a "raised switch box cover"?  I put that in quotes since I don't know what it is called but I found a picture of what I meant (and that is what they call it).  I think it would let you use two receptacles but it would stick out a little further and you may have to find a waterproof version if this is for outside.