It really depends on what compan(ies) you're flying with, domestic tend to have the "as long as it doesn't stick out too much..." where as, if you have a layover in (for example) Hongkong then they'll triple check to make sure you have nothing illegal before they allow you on board --> chances of you being caught are greater. China A. is notorious for being extra strict.
Though I have to caution you to a small detail where the overhead bins were only built to accommodate up to a certain weight, I'm assuming it should be more than the 10kg per person but still...
Add to the possibility of turbulence --> chances are your overhead bin latch might not hold during the turbulence and upchuck your carry-on onto some unsuspecting fellow's head. So I hope you'd consider leaving your heavy carry-on at your feet, sure, it'll be uncomfortable but a bit easier to stowaway.