MikeA, you got the idea. Just make sure you tap the air line into the city fill so you don't pressurize the water tank. Also make the hookup to allow for the compressor to be used for other things like bike tires etc. I am pretty sure your coach will have a house water filter. You will have to drain that manually each time. In addition locate your fresh water pump, it should be above the propane tank, there is a small bowel type filter on the pump inlet side which you may have to empty also. Check it on your first blow through to see if it has water in it, you don't want it to freeze. Just trying to help you out on things that nobody told me!
The anoid rod with the drain is available through Camping World on line I believe. If you are not a member of CW it is worth joining cause they have stores everywhere and great deals.