It’s just a standard sink that flows out the side of the van.
Plastic-molded fish-cleaning sink, with a 5-gallon bucket for wastewater
Small Bar Sink That Drains Into 7-Gallon Waste Water Container Under Sink.
The sink drains to a 10 litre grey water tank on the underside of the van.
home depot small standing laundry sink, not installed yet
Found the perfect sink at IKEA, and then found one for 50% off in the clearance section.
Dometic two burner cooktop/sink with fold down cover