Is it technically possible / relatively simple to enable some kind of a notification / message to be received by the link creator with each payment? 

As I’m using the same Lightning address for all paywalled links (and zaps and other Lightning payments), so it’s impossible to distinguish which payment is made for which paywalled piece of content.

I guess some kind of a dashboard would be the best way to go, but that will probably take a while to implement and may not be on your roadmap at the moment.