"Dressing in the clothing of women," seems to have been a particular proclivity for a lot of The Caesars.
Seems like I have read accounts of similar behavior attributed to The Notorious Caligula, and the same for Nero. Think they also met a similar fate as your Elagabalus. But, also remember that a lot of those ancient accounts are often branded as gossip, or real "hatchet Jobs," designed to assure everyone that they did the right thing, when they terminated The Old Emperor. In ancient Rome, I think "dressing and acting like a woman" might have been a real big justification for murdering a hated ruler.
So, whom would you get to be The Star of your picture? You said the accounts describe him as very pretty. How about DeCaprio? Nobody ever claimed that he fell into The "Ruggedly Handsome Category." He might be an excellent choice.
Peace and Love, Joanie