zoomkat:
There is nothing "wrong" with the current setup, I am more trying to figure out what is generally accepted as "good enough" in these situations.
That is going to be up to you. if you want lower resistance in the wiring, use larger solid copper wires, or skip the copper and use large pure silver wires/busbars. It is your situation, so you are going to have to make the decision on what is good enough for you.
Silver wire of the same conductivity as copper would be 11% heavier and cost 130 times as much, whereas aluminium wires of the same conductivity would be half the weight and about 40% of the cost of the copper. Aluminium is the best choice for heavy current wiring and is used heavily in industry for this reason.
Aluminium would take up 70% more volume though.
For the ultimate a cryogenic system and superconducting cable would give zero losses (except for the power needed to chill the liquid helium!)