Cannot Find 22” Vent Cover

Hello all! I am new to the forum. So please excuse ,e if I am posting to the wrong area. I just purchased a used 2006 American Freedom Toy Hauler that is 21’ long. There is an escape or emergency vent lid that was missing when I purchased the trailer. I am trying to find a replacement lid/cover for it. There is not much info besides the handle that pushes the lid up that says vent line which is held on by one screw. There is also a leftover metal piece that the lid was attached to. There is a number 603 on it. That was all I could find that would help me try to find the replacement lid. The area which the lid would cover is 22” x 22” long. If anyone could help me find or give me some guidance regarding the lid it would be much appreciated.