> The IAU definition is absurd given the current search for exoplanets, because we will be able to detect planemos orbiting other stars long before we have any hope of being able to tell whether they've cleared their orbits.

The IAU definition of “planet” explicitly applies only to the solar system, and the only definition even attempted for exoplanets IIRC is to try to define a dividing line between them and brown dwarfs, effectively “exoplanets” are extrasolar planemos.

> It would be much more practical - that is, useful for actually communicating empirical information - to define a planet as a planemo, Luna, Ceres and Eris included.

I don't see how that follows, since having cleared an orbit is addition empirical information, and information that we are able to develop on solar system objects, if not extrasolar ones, in reasonable time. As is, e.g., whether or not an object is a natural satellite of something orbitting the sun or does so itself.