Dunno how it'd work though. Anything set between Prometheus and Alien runs the risk of being wiped out by future films like what happened with Alien3 and Resurrection. And the post Resurrection time period is the least popular for fans who want pulse rifles and dropships. For everything in between where the only contact with Aliens is shwn in the film, there's only so many stories you can tell that can viably avoid 'history'.