Good job on that garage wiring Paul.
Rebuilding calipers isn't that hard a job really, the hardest bit is getting the pistons out.
And the price of a new set of pistons and seals!! Especially if you have 4-pot calipers
That's not overly surprising if you now have one of the bolts just flapping about
To be fair it's done you a favour well into the minus figures in our neck of the woods tomorrow morning.
What sort of filter setup does your bike use? I'm guessing from your description it's not like a normal canister filter.