What are the constraints on an operon?
From Henderson's Dictionary of Biology 14 ed. An operon is: a type of gene organization in bacteria, in which the genes coding for the enzymes of a metabolic pathway are clustered together in the DNA and transcribed together into a single mRNA. This mRNA is then translated to give the individual proteins. The expression of all the genes in an operon is controlled by a single promoter.

I'm not sure what an overlapping gene is, but according to this definition, yes genes on opposite directions of a promoter or different loci cannot be a part of an operon because they wouldn't be on the same mRNA.