2020 39’9” xlr boost toy hauler. I have heated tanks and supposedly the artic package. And I'm in the cold winter and went to drain the black water tank, which was full. I also found out the main tank drains back into the rear half bath we never use. How wonderful! Anyway the wastegate was frozen on the main tank so got my heat gun out and got it open, great. Then I went to the rear tank and it was frozen to but to my surprise the wastegate is up inside the belly with no access. What now? The grey water is the same way. Yes furnace is on 68-72. Any ideas on how to get these open????