Stuff has arrived and more assembly has happened:
I have almost everything required to complete the cold side loop except for a way to mount the higher diameter pipe to the heat block. I've had some ideas, but I'm just not sure yet. I'm not sure how permanent blutac is.
Still not sure how to practically obtain something safe that can provide 0.5-1kW at 12-48V.
I think I'll start some wiring next and get the water going in a way that will stay in the pipes.