I think the biggest issue arrising from the boxing stance is that its designed to be used with the larger gloves. Whereas Martial Arts that were invented before the advent of padded gloves include more versatile deflection and countering guards and less of the curling up guard.
I've found that a half-distance deflection is the best course. That is to say deflect the attack when it is halfway to to you. This gives ample time to counter, as well as to regain your center of balance all before your opponent has time to do anything but throw on instinct. And if he throws on instinct you've got the time to deflect the second strike, and because it was an instinct strike chances are his guard is low or down entirely, and he's completely open to a knockout strike. Of course defending leg kicks remains just tanking it with a shield or getting out of the way
Of course this only really works effectively for me, and in the case of my Northern Freestyle Mantis Form kung fu friend who tried it, works wonders on under-trained fighters. And that's 99% of the fighters in my area. We've only got one shitty MT school, one decent Karate school/ J3 school, one shitty Karate school and one MMA gym that pumps out BS bangers like its going out of style.