My 21 year old 32' trailer sits in a trailer shed that is open the last 4' on the sides for air flow.
I close all the windows but leave 3 roof vents, with Maxx air covers, cracked about 1/2".
Also we leave the trailer out for a couple of days in the sun after use to dry the interior out. No mold issues.
My son lives in mid FL about 25 miles from the coast. He keeps his trailer in a closed trailer barn with the windows closed and the roof vents cracked open a bit. He keeps three buckets of DampRid in the trailer for their humid environment being close to the coast.
Mold issues vary depending on where one lives and how they battle or not battle the issue.
