P.S. to my last post above. Another thing I did was snap kick them to the groin several times a round. At first it was "Hey, that's dirty fighting, that's a foul!" But I explained to them that groin contact was a standard target in all open Karate tournaments back then. All of them. And it was just a slap to the large groin protector all boxers wear training. So I'd just slap it. Then throw the same thing to their stomach but crack them kind of hard. That was how they knew the groin tap was just a tap.
But if you have it in your repertoire, slap them with a lead leg hook kick, small angle, right upside their head when they're in mid punch. Then, because they'll be looking for that kick, which they don't really understand - I mean, how could they? - pump fake a sweep, only really wide, pull it back and hook kick. You'll smack them again.
THEN - fake that hook, pull it back mid kick and side kick them on the waist line as they attempt to step in. If you catch them mid step, it will sit them on their butt with a wonderful look of confusion on their face.
I love boxing. But I love Martial fighting against boxers even more.