Regarding our Nova Cool refrigerator, there is a little white tray hidden directly under the freezer which I discovered holds much of the freezer ice melt down during defrosting. I assume most R-25 people have discovered the position; i.e., that you can sit on the raised platform under the table, bent over (in kyphosis), to gaze into the refrigerator. I do this a lot in shear wonderment... But, you'll never see the white tray under the freezer this way. While sitting on the cabin sole for some reason, I looked up and spotted the little tray and, curious about it, I pulled it out spilling its contents all over the place. Next time I'll periodically pull it out carefully and dump the water in the sink as the defrosting takes place. Takes about an hour with 72 degree ambient temperatures in the cabin. Some water finds its way down to the vegetable (?) bin at the bottom of the fridge. I wondered why so little seemed to accumulate, until I discovered the tray described previously.
We had very little ice buildup, too. Close the retaining clip while the door is open, and the clip keeps the door from shutting completely. You want to vent a refrigerator, once turned off, to prevent mildew. While towing I close it or prop something soft against it to avoid the door swinging around. I also vent the bathroom by inserting a dock or fender line around the outer door handle and tying it off on the towel rack inside the bath. Since we have a composting head with a constant low power vent fan, this gently vents the entire boat at all times.