Keeping the run cold is definitely the hardest part and you have to do it unless you want the first pint in any given drinking session to be a dumper. If it was me, I'd try to make the majority of the run a 1/4" OD piece of seamless stainless tubing for the beverage and a piece of cheaper 3/8" stainless tubing as tightly coupled to the 1/4" as possible. Wrap that in pipe insulation. The 3/8" line would be fed with water from the same freezer, pumped via submersible pump. It would be more ideal to pump 25F glycol from a freezer, but that's a whole other headache. Once the coolant reaches the tower, it can connect to any kind of tubing for the return back to the resevoir. You'd still want to insulate but outside of the other bundle.
Or you can walk to the garage to pull that pint.