PaulJ2 wrote:
With the few weeks of freezing weather we get around here every year, i don't even drain mine. I just turn the water heater on for the few days. Works for me.
The weather in Oregon is not the weather in Michigan where the OP is.
Odds are the tank is already damaged. Either use external heat like blow drier or reflector light stuck in the area where the tank is to get the ice out or just leave the plug out until spring. I would not introduce any more water to the tank due to the fact it is most likely damaged and will leak into the trailer.