4500 was originally manufactured with two faucets: a hand water pump tap that drew water from the fresh water tank and a city water pressure tap. Each of the two taps used a single hole.
Because the sink is small and there is little space behind the sink AND the fiberglass countertop flexes, I would choose a small, single hole tap / faucet for city water, such as a bar faucet. The other consideration is that your grey water is drained outside the trailer into a container you provide. If the grey water container is small, or if you don't want to be frequently disposing of large, heavy quantities of grey water, then you'll want the water to flow at a low rate, and limit the amount of water used.
We chose a small single tap water filter type faucet for city water use.