WNYBob- Ditto here... cracking two vents and a small side window works great regardless of weather conditions. I don't add dehumidifier or desiccant, not that either would hurt provided they were serviced regularly.
Conversely, I attempted the 'sealed' technique (shut roof vents & windows, then covered with tarp) with the prior rig... nothing but mildew and mold come spring. Never again... conclusion, gotta let them breathe!
I will say, my Pa-in-Law does a bit of a combination of dehumidifier, desiccant, and cracking a vent; he's never had a problem despite also being in the PNW
BBF
1995 F350, 4x4, CC, 460, E4OD w/ Banks PowerPak & TransCommand, factory LS & F/R sway bars, 08+SD finned DC, 9000XL's, airbags
2011 AF990, 2-GRP 27's, 320W Solar, SS-Duo