Big tanks are a good idea if you have lots of snow and freezing weather, however that's not all you need. You will need to insulate your water supply and sewage lines. Most folks use heat tape on their water hose, covered by foam type pipe insulation. Here in Eastern VA I also wrap the heat tape around the faucet and down to the ground. Last year my neighbor showed me his setup. He'd cut the bottom out of a plastic cooler and installed an outlet and lightbulb inside the box. He plugged his heat tape into the outlet and left a 25 watt light burning all the time to keep the faucet and the ground around it warm. He just lifts the lid to check that the bulb is still burning, etc.
As for your sewer line, that depends on what you're using. I use a Sewer Solution (1 inch hose) and just cover it with foam pipe insulation. If you're parked for several months, you might want to fit regular PVC pipe from your sewer connection to the ground. A rigid pipe that's angled down and not lying on the frozen ground may be sufficient to keep the waste water flowing.
I don't know exactly where you are in Tennessee, but if you get lots of frozen weather you'll need to do something to skirt your trailer - keeps pipes from freezing and makes floor warmer, and most important lowers your need for propane. People have used everything from hay bales, to styrofoam panels, to foil backed bubble insulation taped to the underside of the trailer. Some people will have light bulbs or some other small heat source under the skirt as another guard against a frozen water pipe.
I'd vote against hay bales for two reasons: mice and fire hazard.
I'm living in mine in Virginia Beach. We rarely get more than six weeks of really cold weather, so I don't bother skirting my trailer. I do hang a couple of strings of Christmas lights underneath though.
Good luck with your new toy.