Sure, I put some 1mm or 1.5mm thermal pads on top of the SSD controller which makes contact with the input cover sinking the heat from the controller.
I posted a picture here where you can see the repurposed thermal pads I used (hence why they are in 4 pieces and a bit messy) half the thermal pads stayed stuck to the input cover (bottom middle of the picture) and the other half stayed on the SSD controller (the far right square on my SSD).
There is such a thing as paper thin heat spreaders that use carbon fibers or sheets like graphite to conduct heat outward along a paper thin sheet. Phones and tablets use them. But they’re delicate and generally need to be applied like a sticker to something else like the inside surface of the case.
The shiny grey rectangle here isn’t em-shield, it’s a heat spreader. The hot spot is just a little square next to the camera (not the thing with the circles in it, that’s just a block to physically fill a cavity left by missing components so the rear case doesn’t have a spot that could be pushed in) The graphite sheet spreads that out over the whole larger area.
