We have live in Bremerton for about 25 years, about 6 of those were in our 5th wheel. The winters are usually mild, but we do have snow quite often. It usually only lasts a couple of days then melts. That said, last year we had quite a bit of snow (8-10 inches) and the cold weather keep it around for a couple of weeks. I don't believe you would have any problem as long as you use common sense. When it going to freeze fill up your fresh water tank and disconnet your water hose. Use your electric heaters to supplement your propane heater. You need to keep your propane heater on to keep your tanks (water, gray and black) from freezing. If you can you might want to lease a larger propane tank ( it keeps you from having to refil yours every 3 or 4 days and it the propane is cheaper in the long run) If you have a problem with your black water valve freezing shut use a hair dryer to unfreeze it; your gray water valve will be open all the time so they should'nt be a problem. Use an electric blanket at night, but keep your propane heater on for your tanks and under compartments. If you have any questions you can email me and I will be glad answer them for you.
Good Luck
Bob Williams