A heated floor pad sounds like a good, practical idea. I'm going to Google it.
I put heated elements under a ceramic floor in a bathroom a few years ago, and I loved it. No, it doesn't heat the room as such, but it is surprising how a little heat in the floor makes the room feel warmer. And the power draw was reasonable: I think around 150 watts, and it maybe was 'on' half the time, or less.
That house had a concrete floor rather than what I have now: a crawl space. The floor got SO COLD in winter, and the room was in a corner of the house. On my last trip out west a few weeks ago with a 5th wheel, we hit temps around freezing at night. I thought then, how nice a warmed floor would feel . . .