Electric Heating Pad - 10cm x 5cm (ADA1481)

I am looking at heating a composting toilet in my caravan by building a special base plate to accommodate two of your 100x50 heat pads wired in series. The power supply is 13.6 volts. So I have two questions:

  1. On my rough sums they should reach around 63 degrees. Does that sound about right?
  2. What is the insulation material on the supply wiring that comes with the pads? Will I have to replace it with high temperature wiring?
    Best regards
    Keith