You know, there is a big difference between glass having a light fog of condensation on it and having larger water drops that slide down the glass. No amount of miracle anti-fog solution will prevent the latter. It's simply a function of atmospheric humidity meeting a cold surface. There are two ways and two ways only to prevent this: lower the humidity inside or warm up the windows. This second method is not easily accomplished, though snapping insulated canvas covers over the windows from the outside can help.
Your new diesel stove is really going to eliminate almost all the concern with this. Cold air is dry air; cold air holds little humidity compared to warm air, which can hold a LOT of water vapor. Many boaters underestimate the large amount of water that they exhale during sleep. Remember the days of fogging up the car windows when out on a date?
When you turn off the heat and turn in for the night under your snuggly down comforter, the inside of the boat cools off and all that exhaled moisture condenses on the windows. Of course, it condenses in all sorts of places you can't see, too. Mold and mildew ensue.
But with the new stove you'll just turn it down to its lowest setting at night. With the inside air kept relatively warm (it doesn't have to be summery inside), it will hold a great deal of moisture. It will also warm up the glass a bit, which will further reduce condensation. HOWEVER...when it's quite cold outside, you'll still have condensation on the inside of the boat.
So the real trick will be to use science to your advantage. As you and the admiral sleep, exhaling pints of water vapor, you'll want to pull cold, dry air into the boat. Warm this dry air up and it will "absorb" all that moisture. Then push the warmed air outside...it will take all that moisture with it.
In my boats I've always had wonderful success with this simple method. Assuming that we sleep forward (your mileage may vary), we draw in cold air astern with a small boxer-style fan. This pressurizes the interior of the boat. The diesel stove on its lowest setting heats the air. The warmed air moves toward the open vents at the bow, taking up buckets-full of moisture before leaving the boat.
It's amazing how dry the inside of the boat can be with very little effort.