By saying that something is impossible to do cost-effectivey, one is implicitly claiming they have rigorously combed through the whole problem space, all possible configurations and materials, and exhaustively concluded it is not possible cost-effectively.

Imagine now instead of a pyramid, a cone. Imagine the cone is spinning along its symmetry axis. One now has a local radial pseudoforce, a fake gravitational force along the radial direction (away from the symmetry axis).

Now any fluid with a liquid-gas phase transition above the desired radiator temperature but below the intended maximum compute operating temperature (and there is a lot of room for play for fluid choice because the pressure is a free parameter) can be chosen to operate in heat-pipe fashion. Suppose you place the compute at a certain point along the outer rim of the cone, and fluid that condenses on the cone wall will flow to the circular rim at the base. the compute is inside a kind of "chimney" and the lower half of the chimney (and the compute in it) are submerged by the fluid. The fluid boils and vaporizes, and rises up the chimney and is piped to the central axis and flows out in a controlled distributed fashion. all of the pipes could be floppy aluminum foil (or mylar etc.) pipes, since they are all pressurized during normal operation.

Some of the liquid phase could be pumped up to the central axis at the base and cool the rear side of the solar panels as well. I don't see the problem. The power density of solar panel heating (and thus power density on the cone surface) are very similar and perfectly manageable with phase-transition cooling /condensing.

At some point you are just prodding until people hand you working designs on a silver platter.