Make a cornice out of cardboard and attach it to a curtain rod to hand it. Maybe do a tufted one to match headboard
Tutorial on how to build a pelmet box window cornice using foam board instead of wood.
Fabric Covered Cornice Board (& How To Hang It!) - Shine Your Light Just in case we--I mean they--decide to do this!
Cornice boards, classical molding, chinoiserie wallpaper, gilded mirror--just beautiful!