Teardrops n Tiny Travel Trailers

I just noticed that my air vent cover is completely gone I am considering putting in another one or just covering it,
I regret not having the fantastic fan installed but the factory said they had not installed one and talked me out of doing it.
I have had my trailer for 7 years and I almost never use it I have a window and screen door and the rear is all screen also,
I watched a video it looks pretty simple to install but I wonder if I should take the easy route and just put a cover over it and not even use it ?
I would like to hear from those that have replaced the vent and which of the vents to use the fantastic fan or the maxair brand
it looks like the vent and the install kit cost almost 200.00

I replaced just the plastic lid to the vent. Ace Hardware, about 10.00 and 10 mins. Then I took that vent out and installed a Coleman Mach rooftop A/C, and bought a new combo fan, light, vent and installed in bathroom. All of those were straight forward. All use 14x14 hole in roof. You'll need a power wire. Butyl tape and lap sealant. Easy.

McDave