Generally speaking, "relevant in lots of countries" translates to "NOT RELEVANT TO ANY COUNTRY IN PARTICULAR COUNTRY", and therefore "not listable anywhere in Regional at all".
So you should look for your one listing in Shopping, Business, or some such place.
You mention site "competing". This is irrelevant. We don't care whether it competes or not. We care whether it has unique relevant content.
"Works off variation of URL" is a wierd long way around of saying "deeplink." We don't care how you do your deeplinks: vanity domains, subdomains, subdirectories, query strings, wierd and untraceable forms values. They are all the same to us, except that if they look out-of-the-ordinary, we wonder what sort of sleazy scam the submitter is running.
Just submit the main URL in the single most appropriate, non-country-specific category.