Large water tight plastic tray or lid (freezer defrosting) (Wood Farm OX3)

Hi. I need to defrost a badly iced up freezer for an elderly guy. It is on a chipboard floor, so I cannot let the water run out. Ideally, I need a large plastic tray with a shallow profile (ideally not more than 25mm high) or a plastic crate lid? that I can slide under the front to catch the water. Ideal size 450 - 550 mm wide x 300 - 750 mm deep. Thanks for your help.