Yeah but no but... No. Mostly.
Things don't steam up because they're cold. They steam up because they're cold and they're brought into the warm. Like my glasses every time I go into a shop in the winter. What's happening is that the air that comes into contact with the cold object is cooled, perhaps quite significantly so, and cold air can't hold as much moisture in it as warm air. So you have warm air with moisture in it, you cool the air, the air can no longer contain that amount of moisture, and hence you get condensation on the cold object.
So whilst you're actually out shooting in Iceland, this isn't going to be a concern. Condensation is only going to be a problem after you've been outside shooting and you bring the gear into a warm building or a warm car. I hope it's obvious that a screen or filter or something isn't going to prevent condensation; you'll just get the condensation on the screen or filter instead of on the camera or lens.
The best approach is to have a ziploc bag to put the camera in. Put it in the bag whilst you're still outside in the cold, squeeze as much air as you can out of the bag, and then seal it. When you go into the warm, you'll still get condensation, but on the outside of the bag where it won't affect your equipment.