12VAC water heater and water pump. Managed to fit it all behind the sink drain pipe so cupboard is still very usable. Drain goes straight out the bottom to a hose fitting for grey water catchment if desired.
AC water heaters are generally1400W, make sure you have a big battery, inverter, and/or alternator charging before you try this. I mostly just heat it as I drive, the water will stay somewhat warm for up to a couple days. I can turn the inverter on or off from the cab while I drive. Can also monitor house battery status from smartphone to make sure all is well.
PO had a convoluted drain snaking through this and every other cabinet on the kitchen side of the camper before it went out the back. Pretty much made all the cabinets useless.