With a forecast of 29...you should be fine. Keep in mind that typically it won't reach that 29 mark till just before sunrise...normally when there is frost forecast, the temp will drop a couple degrees just before the sun comes up, and it will rebound quickly once sun is up. Also your hot water tank is insulated, so with it getting to just 29, that wont freeze whats in the hot water tank. Its in storage so obviously you aren't concerned about any city water connection or sewer connections. Your plumbing inside the trailer will be fine as it will be a few degrees warmer inside the trailer than out.
2011 GMC Sierra 2500HD
2014 Rockwood 8289WS, Diamond Pkg.