My 2 year old Kodiak came with the regular cheap feeble plastic vent lids; one in the bedroom and one in the bathroom. The first modification that I made was to replace these cheap vents entirely with Maxxaire vents. The reasons for my choice were as follows:
one had a remote control (put that in the bathroom)
they are quiet (no concern about noise in bedroom)
they can both be open in the heaviest rain or in transit with no water or dust getting into the trailer
They both push or pull air as is the best for the situation.
they sit nice and low to the roof of the trailer (rather than the covers designed to go over a regular vent.
Downside........only one. Cost! They were not cheap!
Would i do it again? You Betcha I would, its still the best mod I have done.