Feeling forced to be the house supervisor

Been working at this SNF/LTC for about a year. I have never been trained to be a house supervisor. I work night shift. Recently, my house RN supervisor just went on pool to be full time at another place. Therefore, I have a feeling that they will ask me to be a supervisor because I will be the "only RN" in the building. This is alarming to me. The scheduler recently called me asking me to speak with the ADON, but I have not replied yet because I know what they will ask. I do not feel safe to be a house supervisor in this place and feels like I will be thrown into the position. At night, the facility, which consist of 176 beds, does not have full time staff and mostly consist of agency nurses. The rehab floor is 12 hours shift (2 nurses at night) while the LTC and Dementia unit are 8 hours shift (1 nurse at night). At times, an agency nurse/ staff nurse will call out and will not come to the LTC or Dementia unit. Therefore, the house supervisor will take the whole floor with 2 med carts for at least 60 people and be the house supervisor at the same time. The facility is very disorganize and understaffed. Also, they do not pay as they promised. I know someone who is pool RN and was forced to be a supervisor to several shifts to find out that they have not paid him for those days. They recently made supervisors as "salaried pay" in contrast with hourly. I am planning on leaving soon and want to find a job that is somewhere closer to my house. The commute to this facility is about 1h and half. Anyone have experience like mine?? What do you suggest I tell the scheduler or ADON?