Until you or I write it, :rolling: , there is no one comprehensive source for the less common body mods. At most you get a chapter here or a chapter there.
You'll have to glean what you can from the odd chapter or section here and there. Other than the two books you mentioned, I'd recommend any and all back issues of Fakir's bodyplay magazine from the 80s and 90s, www.bodyplay.com
I'd also recommend a new book called ModCon: The Secret World Of Extreme Body Modification by Shannon Larratt. That one is mind-blowing. Some of the old PFIQ issues had some stuff on branding or cutting if you can find them. Also good is The Customized Body by Ted Polhemus with pics by Housk Randall