Just to stir the pot a bit, assuming it might be filled with creative juices, I'll ask a question. Why build a sink for the print-tray line at all?
It seems to me that the whole concept dates back to the days when there was no thought given to water or power conservation, and a continuous flow of temperature-controlled water was used to keep the tray solutions at the desired temperature. In the old days, I could use 1,000 gallons of hot water every day, and it would still only cost me $9.00 per month ("flat rate") for the water and maybe $15/month for the gas to heat it. At today's rates, I'd never be able to afford doing the same thing, even if I weren't reasonably conservation conscious.
Absent the tempering water bath, the only purpose the tray sink serves is to control spills. Temperature control is easier to accomplish via controlling the temp of the ambient air (unless a cast-iron sink and water pipes are acting as a heat-sink to the ground), perhaps combined with the use of a heating pad or aquarium probe. In some 40+ years of processing, I've never spilled a full tray of anything. A couple of drops, perhaps, as prints drip when going from one tray to the next, but never any substantial amount.
So, to me, a prefab inexpensive counter top from the local building supply would seem completely sufficient for the print tray line. That's essentially what I've been doing for the last 10-15 years, and it seems to be working. Am I missing something?