I have done what is recommended in the notes. One winter the heating in my apartment failed, and the heater was so obsolete the replacement parts were unobtainable and the entire system had to be torn out and replaced. We decided to postpone it until spring when cutting the walls would be less of an issue in exchange for a reduced rent. I just moved my Sun workstation to the top of the kotatsu and worked like that. The cats loved it.
Truly, the kotatsu is the greatest miracle of human invention.