Why not keep the wlp835 for the winter and just put the fv in the coldest place you can find, I wouldn't worry if it was a few degrees hotter than ideal.
The brussels brett is supposedly a Cantillon blend so perfect for a lambic, brew it and stash it away for a couple of years and it'll be great.
The 644 looks great too, one I've been wanting to try for a while in something like an IPA. It's not a brett strain but it has a lot of similar flavours.
Thanks for the advice. I keep wondering if I could ever make use of my balcony for brewing lagers, but I suspect even with wrapping the FV in lots of insulation it wouldn't keep a consistent enough temperature.
I'll investigate doing a lambic with the Brussels Brett. I think I was thinking along those lines with the Mélange, but I think I was thinking along the lines of having two vials of it might make up for them being out of date. ,