I am looking to get a heat pad/pig blanket for Lana this winter. I will be keeping her in a room in the basement. The room is actually a wine seller with stone walls and no window and it's about 8x10' I have a heat lamp now to keep her warm at night and will be getting UVB for winter also. Lana is 12'' and weighs 13.5 lbs. What size pad do I need? Does it need to be bigger than her and by how much? Should I get one that she can grow into? I also have Tank that is smaller so he could have it if she outgrows it and get her a bigger one. Advise please cause these things are not cheap.