I think you'd be better off putting 10mil plastic down, mylar on the floor can be a safety hazard. it conducts electricity, and is mostly flamable plus the cheap stuff I use gets torn and wrinkled up really easy. really I'd put down good thick plastic on the floor just for spills.
You could cut mylar circles out (shaped like pac-man) and put on the surface of the pot, just makes it harder to water though.