Wayne, my wife and I just got back from shopping for a 5th-wheel for the very first time. Like you, we are looking for something to full-time in. According to our sales rep., the 'Four Seasons' claim of some manufacturers is very optimistic, at best. His advice is not to count on keeping your lines safe from freezing below 0 degrees Fahrenheit, which is far short of your -30 (F or C, doesn't matter at that temp.). I am sure that there are RV manufacturers in Canada that make what you're looking for but I doubt you'll find a U.S. manufacturer who meets your requirements. Just my 2 cents.