i'm in the same boat as you...i'm 5'5" with around a 28.5" inseam (barefoot with feet around 3-4 inches apart). i BARELY have barefoot standover clearance on my '07 specialized roubaix (XS, 49cm). we're talking like 1mm clearance!!!!!
so like you, my search for a cx bike has been frustrating and exhausting!!!!!
in my internet search so far, the only frame that i'm POSITIVE will fit is the bianchi axis...
if you don't mind me asking...what's your inseam?