Soft bitch hands are the opposite of your problem, it's actually the reason people choose hook grip as per George Leeman on youtube, check one of his videos where he explains how his callouses tear on mixed grip because of the bar rotation. I mean small hands as in short fingers etc. You have to fit as many fingers under your thumb in order to hold on to a barbell in a hook. Mine is 4 fingers in and so is my front rack but my fingers are on the longer side of the spectrum. As per above you can tape your thumb and also you can put a tape around the knurling to prevent callous tear until your build up your hook strength which is different compared with regular grip strength.