Again, the heat tape will be covered. It would be from bottom layer to top layer: Melamine (subfloor if you will), heat tape w/probe, linoleum or better product I can find. It is basically the same thing you said earlier I just perhaps phrased it wrong. There is no way that the heat tape could heat properly through 3/4" board. That is what the layer of linoleum or acrylic is for, to go over the heat tape.