O"Brien in his book, as far as I remember, makes no mention of Boho. The unusual word itself brought me in mind of round towers.
The surname Boe was at one time most prevalent in our Isle of Arran where one finds many ancient stone structures and if any credence can be given to O"Brien they could have arrived here at an early period and been known by the place they came from, surnames only coming into use at the end of the 11th. C.
What is the current thinking on O"Briens work, he certainly ruffled a few feathers at the time of its publication {pun intended J.M.} in the early 19th. C.
When discussing the subject with a friend at the weekend he thinks that the remaining part of the round tower house of Orchardtown in Galloway may have been the base of another round tower in Scotland