Hey Dan. David Witton posted about his cover here
As as far as moisture goes I've wondered if a plug in gun safe dehumidifier would work. All summer I've kept my boat in my carport so it's quick in easy to go fish. However in this wet Georgia summer I've gotten a little mold. In the winter I'll keep her in the garage/workshop but I'm thinking about summertime options. I would think a good cover and a dehumidifier would be a good combo but who knows.
I'm really happy with the cover I got from Montana Canvas a couple of years ago. It's great for storage, but also for trips down gravel roads to the put in, where pebbles get kicked up from the truck tires and can chip the finish coat on the boat. One improvement I've made this last summer is a tarp rigged over the boat to keep direct sun off. When the covered boat sat in direct sun, the temp inside the cover must have been 120 or more, and I could see signs of the wood drying out more than I liked. During the colder months I don't need the tarp, but during the summer it sure helps.
I have a cover made in Oregon by 5 C's Boat Covers. It's five years old and is still like new. Check them out.
I have a cover from those folks, too, and I think it's terrific.
Do you have room for "Costco garage"? At ~$150, it would give you decent snow-shedding ability for 2-3 winters (seems to be max lifespan of the tarp cover).
We don't have super wet winters here in MT, so I would think if you can keep snow/rain out of the boat that you wouldn't need to worry too much about condensation inside.
I think the MT canvas solution would be ideal for summer storage and travel.
I had a boat cover on a motorboat a couple winters, and it was a huge pain having to shovel after every big snow--and it was still musty inside when I opened it back up.