Andy at Inland RV
has a sale going through March. At the above website you can match the vintage of your trailer to a photo before you order. Scroll down until you get part numbers in the 65XXX range for Ceiling Light Lenses.
If your window and compartment door (battery, fridge) gaskets are cracked, dry or crusty take note in the 45XXX area. And your 2 Vent Pipe Gaskets (#45701) may allow leakage too. Just trying to help you control water leakage and prevent floor rot... Do searches on some of the above key words if you want more info (window gasket, vent pipe gasket).