Yup, I've tried many years ago to follow this work (special cases for even and odd exponents!), with a mix of analytic and numerical integration. IMO linear/tent filter is sufficient. Also more recently there's the Linearly Transformed Cosine stuff, which is most of what people usually want in realtime graphics.

Ideally you also want motion blur and probably some other effects, so IMO it just makes sense to use a 2D BVH and high efficiency Monte Carlo importance sampling methods.