I suppose they could pull a properly sized feeder and install a small subpanel to an area within sight of the equipment, then run the needed branch circuits to the water heater from there.
One thing though… I know that the SQD QO 6/12 circuit panels I have are only rated at 100A, so not sure if they are available with a higher ampere rating.
If not, then one possible problem might be if the feeder were sized only as needed for the water heater loads but, a larger panel was install installed because of the needed higher ampere rating. Someone else could come along later and run additional circuits out of it to feed other loads.
