Four season camping or Extended season camping?

Some manufacturers make claims that their travel trailers are FOUR SEASON campers while others conservatively advertise EXTENDED SEASON. The difference? Four season would allow you to camp in the middle of winter ANYWHERE in the continental US. Which would indicate that your water system and holding tanks are fully insulated and heated. Extended season would mean that you could camp in COOL weather up to the point of freezing. In my opinion, why settle for extended season when you can go all the way and camp through out the winter? Their are different levels of protection available for the cold weather camper. Some manufacturers wrap the under belly of the trailer with a plastic membrane and stuff some fiberglass insulation in for good measure. I appreciate the gesture but I can't believe that this would be enough of a precaution to allow cold weather camping. Others duct their heat into the compartment surrounding the holding tanks to offer another level of protection. This works well as long as your furnace is running constantly. I don't know about you but I'm not crazy about having my furnace run while I'm traveling down the road or while I'm away from camp for the day. The third option which in my opinion is the BEST, is an electric heating element that warms the holding tanks. This is a 12 volt system that will run off of your 12 volt battery while you are traveling down the road and can be left on when away from camp without running yourself out of propane. When you are plugged into a campground electric hook up, the campground pays to heat your tanks, not you. In addition it is better for the environment than burning propane constantly.  Though your tanks are heated with this element, not all manufacturers wrap the water lines. While your holding tanks are nice and warm, the water in your supply lines may be frozen. You'll need to investigate this when looking into a trailer with heated tanks. Some will run the supply lines closer to the center of the trailer but some designs have the water lines running the entire length of the trailer exposed to the elements. Another great option is to upgrade to a On-Demand water heater. Aside from the fact that you can take a longer shower than with a traditional 6 gal water heater, there is no storage tank in a On-Demand water heater. Which means you have one less potential for freeze-up. When shopping for a new travel trailer or RV, make sure that the manufacturer that you choose has taken all of this into account when designing their cold weather packages. If you have anything to add to this post, please do so. Also, any tips or tricks to cold weather camping will be appreciated.