I'd like to suggest reaching out to the folks at CinemaVision and utilizing it in the upcoming vesion of OpenPHT. Plex's intro and Trailer setup is minimum viable product solution, while CinemaVision is the gold standard, IMO. Since CinemaVision is a kodi add-on, perhaps there would be a way to toggle between using it and Plex's trailers feature?
From CinemaVision's website (https://cinemavision.tv/) :
"Build a unique cinema experience that brings the magic of movie theaters right to your home. Customize your preshow experience with trivia, short films, trailers, video bumpers and more, and even control your home automation solutions during your preshow."
I'm cross posting a feature request in their forums, to try and drum up interest on both sides. :)