Dr.  unfortunately my HD requires a water flow of no less than 2gpm – so using the .05 aerator to reduce the flow is not an option that I can use.

I have to be able to fill all 3 sinks 2/3 of the way full with 110 degree water – and at 11 gallons (2.3rd total) that would take over 20 minutes to fill them, which is obviously not too practical.

But hey, if your HD doesn’t have these type of stipulations – then it’s a suitable option.

I have no clue as to what the above means? But when I wrote “in minus 2 degree weather this winter and my water coming from a holding tank outside my trailer (with the tank water temp at just above freezing, my instant hot water tank heater, heats my water to the point it’ll steam when we fill a sink. But the setting on the tank-less heater needs to be at Max Heat, and the water setting at low volume” that is not going to reduce your hot water flow to under two gallons per minute and I never mentioned an aerator? I’m lost here, but it doesn’t matter you have a regular water heater now.