generally speaking, ventilation is key for campers. the humidity comes from your own breath. but honestly, if I was living in it for a long time in one place, I would most definitely try a dehumidifier.
This is the window design we have. Can leave them open in the rain and still have good ventilation. they even lock from the inside when just barely cracked open. On the inside is a roll-up shade and a roll down screen that snap together so you can choose airflow and sunshade rates.
A year ago I snagged a couple jacks from the junkyard to take the bounce out of the middle of the trailer. Works fantastic! Plus peace of mind if you ever get a slow leak in a tire. also be sure to get a pair of those X braces that lock the tires together on a dual axle trailer.
Weird that some people have that issue but others don't. but glad you were able to make it work.
Got a pic of the interference? Maybe there are some unknown differences in the t-cases over the years.
It's a brand new tow rig with a built-in controller. Manually activating the brakes felt like I should have more braking, but was prepared to chalk it up to not being used to this particular combo yet. Shoulda gone with my gut and did a more thorough inspection right then and there. Fortunately the camper is only 3500# and the Durango is more than capable of stopping that much weight on its own.