Rich- Good timing on your question. I just slapped together my sink for my TD and got to test the components over a 3-day boondock weekend in the high desert of Oregon, so I can speak from experience now. I originally purchased the Reliance On-Tap Powered Sink (
http://www.rei.com/product/752731) in order to simply sit on a table extended off the galley, but once I got it decided to lose the actual sink and keep the faucet and pump. I then installed a steel enamel sink from an old trailer into the table that extended off the galley. The sink simply drains into a Jerry can and the pump draws from a Reliance 8-gallon roller tote.
The pump plugs directly into a 12v receptacle that I added into the galley counter and runs off the deep cycle battery. It also has a battery pack that holds 8 D batteries and the pump simply plugs into a 12v receptacle in the battery pack (if you want to run off D batteries). The pump on current models is rated at 1 GPM I believe (I called to ask) and they are going to move to a higher (1.5-2.0) pump shortly as they introduce a Zodi-type water heater. Anyhoo... the pump puts out enough H2O to effectively do dishes. Tied into my Zodi heater (which had a 0.8 GPM pump) makes the chore easier for greasy pans, or when its cold and the fingers are freezing. It does take some diligence to keep water usage down even with the small pump, but it is possible due to the fact that there is a on/off valve at the faucet head which kills the flow of water, but the pump can continue to run without damage. So you don't have to turn the pump on and off to conserve water. I was surprised that on the first day I went through 5-gallons just doing a couple sets of dishes, before becoming more diligent about consrving water. I would say 3-4 gallons a day is enough to handle dishes for the day if you are moderately careful maybe 2-3 if you are really efficient about water usage. That's just my experience from one weekend. In terms of power usage, We ran the Fantastic fan on the 10% setting (can't say enough about the Fantastic upgrade kit which allows micro adjustment of the fan speed) all night for 2 nights and lights a couple hours and the DVD player about 30 minutes. My cheap battery meter went from 12.8V to 12.4V (80% charge) over the 2 days the trailer was set up and used. So I was happy with overall power consumption.
You can buy just the Reliance pump/battery pack and a shower head for about $30 and if you contact them directly-
http://tinyurl.com/5vf3n5
I bet they would send you a faucet attachment as well (they are nice folks up there). I also like the water tote on wheels (though I did crack the lid/spigot by tightening down too hard on it, so I need to get another) and will get a 2nd one to replace the 5-gallon Jerry can for the gray water from the sink- that way they match up in size.
All the best!