I'm fed up with dealing with wet, crumpled, and torn parchment paper, so I designed a 3D-printed divider for medium-sized trays. They can fit in it and aren't too tight, but they should allow you to use the entire area of the tray. Printing two of them will completely cover the tray. I recommend using ASA material to make it dishwasher-safe. At least in my dishwasher, PETG will melt.