I have a question on the proper vent cover to put over the fan in the bathroom of my trailer. I purchased a Maxair vent, but my son does not seem to think it will work with that vent. Do I need to purchase a particular cover for a vent with a fan in it? The issue he was having is, the screws did not seem to be adequate to drill into the side of the vent and into the fan housing. Are longer or special screws required? It is a 2012 Rockwood Mini Lite 1905