Before storing indoors I left mine on electric and the diesel boiler turned on with the Tstat at 40 degrees. If the power went out I had enough battery amp hours for several days of operation although it was parked at my house where the power never went out long enough to worry. By leaving the heat on I've never winterized this MH and we can have single digit temps.
OP, if you have power when stored I'd be tempted to do the above if I lived close by. Using and tasting the pink stuff in a previous RV once was enough for me. Florida is only two days from Delaware.