Run Away to the Circus... Regency Style!
Bring a Boxer to His Knees (release date August 2022!) features a circus strongman/boxer as the hero and a burgeoning circus sharpshooter/trick rider as a heroine.
Basically, it's fun times, and it required some super fun research. Below is a list of links I've used to research: Astley's Amphitheater, Regency era pistols, nineteenth-century strongmen and boxers!
http://www.reginascott.com/box.htm (details of boxing as well as social customs surrounding it)
http://historicalromanceuk.blogspot.com/2012/03/regency-boxing.html (boxers could make anywhere from 50 pounds to two thousand pound purses! But was a lucrative trade.)