Warm boat under cold deck... Will insulation on deck, under the wrap, take care of the condensation?
Warm, Dry Boat...is this a book or a thread on sailnet?
I think the main thing that takes care of condensation is ventilation. The "greenhouse effect" of the plastic covering itself tends to warm the air above the deck considerably, so the goal is not so much to warm that deck, but to either minimize the difference in temperature between the inside and the outside, and to draw in cool, dry winter air and to expel warm, damp air.
Certainly insulating the INSIDE of the boat can do wonders, because the boat is after all sitting in very cold water, if not ice.
"The Warm, Dry Boat" is a self-published book about ventilation in general and the various appliances (heaters, stoves) that are best suited to keeping the boat comfortable and dry. You can Google it.
If you have a big boat, and have easy access to the shore, the general consensus is that coal or hard woods are the best fuels, because they are inherently "dry" fuels, unlike, for instance, propane. If you've ever run a propane stove on a cold boat, you'll soon see condensation unless it's vented via a range or some other type of exhaust method.