Keep in mind I am retired, fish and travel a lot. My camper does not get tucked into my garage to intermittently dry.
I was not saying inside is an "Extreme" problem. If that is what you gleaned from my message read again. I was referring to exterior environmental conditions. I have figured out how to manage it and passing it on. What I refer to is extreme exterior conditions. There are periods for weeks at a time for instance in the Hoh Rain Forest on the Olympic Peninsula where it is 100% humidity drizzling rain and once in a while mixed snow that makes for the perfect condensation battleground. Forks vampire crap you know. Moss is on everything N., S., E., or West. There are mountain rain shadow micro climes even here that I duck into to dry out sometimes, but unfortunately that is not where the Steelhead are.. All I'm saying is that in a Rain Forest you have condensation no matter what and if you can manage it here you are good to go. I was in SoCA Laguna Beach and not even a hint of a problem, or anywhere else that I've been in Ca for that matter. I don't consider Terrace to Smithers a rain forest. Smithers to PG is absolutely not. Below Terrace to Prince Rupert, yes, but my opinion not as wet as the Hoh Rain Forest. I have also been to Haida Gwaii, Yakoun River and that it a step up from the Hoh in terms of cold humidity. Also, fall is one thing, Winter is quite another. If you were saying Extreme conditions don't exist, well, I'll be nice and say no more.
Picture hearing no rain on the camper roof other than maybe varying degrees of hissing. Rain usually sounds like a drum, right. Yet go outside and you are drenched with water rolling off your brim almost immediately.
I have a rear awning and shake off as much dampness from clothing as can before getting back into the camper, but once that clothing is inside the water vaporizes and condenses against anything cold. There are many other sources that cause vapor and I try to minimize. When cooking the vent is on full tilt boogy exhaust and the turnbuckle door is open. No pasta in these conditions, I wash dishes in cold water. Get inland and not a problem, with the exception of under mattress. If you don't keep ahead of it mold and mildew will eventually show. Use judicial amounts of heat, Vent and dry and it is manageable.
With re to dehumidifying packets. No, I think they would be to much hassle when picking up, running and gunning all the time. May work if in storage, but so far mine never has been in storage.. When things get a little clammy I head to a laundry. Better yet with preventative maintenance it doesn't get clammy.