I suggest that you chat with gardeners in the PNW forum. Many of them garden in cool, moist winter conditions and can tell you what works and what may not during ( or thru) winter.

Here is a link that might be useful: PNW image

I was wondering if the wall-o-water idea would work for a large (4x8x3)cold frame.I plan to take 2 liter pop bottles and cut the bottom off and stack and silicone them until i get the desired height and use that for 3 sides of the cold frame.I'll fashion a 2x2 frame so I can top it with an old glass shower door ,enclose the 2x2 frame with the water filled bottle stacks taped or glued together.I'm not sure if the water towers will hold enough thermal mass to keep that big of a cold frame warm in my zone 5 garden long enough to add 4 to 6 weeks to my growing season which ends in mid sept.in my west central michigan garden. thanks