Trim it out to hide the access door . Maybe vertical trim equally spaced to make it look like intentional, well thought out trim work.

This is builders trick to make you think you have useable storage. Unless you are family of trapeze artists you won't use this. Make it disappear visually and save yourselves potential injury. Also the ledge will grow large dustbunnies, best to eliminate it with wallboard.

I would not add trim. I would create an opening with what is known as an A-200 drywall bead (USG calls it L Trim) at the edges of the drywall and then take a piece of MDF material to make an access door. This trim is nice and clean on the one edge (the edge that would face the opening) and has a drywall corner bead type face for placing the mud.

The door could either be mounted with 5 way Blum hinges or SOSS hinges so that the only thing you would see would be the two vertical lines running down the sides and the lines at the ceiling line. Bottom line is that that access should NOT be the focal point of the room.