I have one silkie (came for free with the Seramas specifically to help with keeping them thru winter!) and because I have so few birds, I can get away with a small enclosure, and a heat lamp. It makes it easier to cope with the cold, having so few, but harder to deal with water. Most of the heated water options are too big, or too open, to work in the small space I have. If I had more birds, I would do what you're doing and put in a floating or submersible tank heater, in a much larger volume of water, or go with a commercial heated waterer that would work for more birds in more space and could be hung to keep the crap out of it.
I didn't find the Seramas harder to keep over winter than the large birds we had when I was a kid, and only one tiny comb bump got caught by frost last winter. This year I have a run attached to the shed, and may consider some changes to let them have more space. The challenge then is that the Silke doesn't fly and none of them seem interested in using a ramp...so providing heat will have to be reworked - although not heating is just not an option for me.
I'm fine converting C to F with all the converters online, but wasn't sure just how cold it got for you. -26C can be a challenge, but if you get sunshine, and they are sheltered from wind it's not too hard to get the temps up to -10C or so, and even my Seramas were ok at that. It sounds like you have things figured out, though.
I can only imagine how productive Silkies are, as mine has been very determinedly broody this year even with no eggs at all. Maybe next year I will let her sit on some, but we really don't need more birds here, as it would mean ramping up scale on everything! Since we're on a city property, and a fairly small lot, I think we're maxed out already...