This almost feels like cheating. Why not count hair follicles with hair attached then?

That's very different; hair doesn't perform membrane transport along its length. The surface of an axon is critical to the cell's functioning.

https://en.wikipedia.org/wiki/Axolemma

In addition to what mbauman said, hair follicles and the hair itself are not single-cell. I can't immediately find the composition and average cell size, but even a long and thick strand of hair is less than 2 orders of magnitude larger than the largest neurons. I doubt any individual hair cell is very large.