Need advice -- removing ceiling a/c cover

We have discovered that in very cold weather, condensation forms in the a/c unit and drips out of the vent on the ceiling, onto my head. Which is unpleasant, since I have no hair.

So I am thinking about putting in a temporary piece of reflectix inside the ceiling fixture, so that the moist air inside the trailer does not condense on the metal parts of the a/c. I am not sure that is going to work, but it might, and it is worth a try.

I undid all of the mounting screws that I could find (there were six of them around the perimeter of the cover), but the plastic ceiling cover seems to be fastened onto the a/c unit somewhere in the middle, where I can't reach (or even see).

So that is my question -- does anyone know how those covers are fastened onto the a/c unit, and how to get the cover off without breaking it?

Thanks in advance for your advice!