Main character Julie works as a model and at a certain point has her beautiful locks shaven off her head for a particular commercial ad campaign. She gets a satisfaction from feeling her bald naked head which induces her to keep her head shaved for much longer than needed.
When Savannah Rebels sports-pro Jimmy Bronson sees the billboards he instantly falls in lust with the hairless woman depicted on the billboards. To his joy he finds her living in the same apartment building where he lives.
This novel is Jimmy and Julie's romantic story. Because as it turns out they have a few things in common. They both like bdsm sex, of the very mild variety. But their main connection is their mutual fetish for bald, naked, hairless heads and the shaving of heads to render them so.

If I remember correctly the Sackmaster part of the novel title was a nickname for Jimmy, but the Necessary Roughness bit might be misleading, as the erotica bits are quite light in nature.
Recommended for readers with an interest in the remove-hair-from-head fetish. ( )