Francois, if you won't be offended by a suggestion, it occurs to me that a length of tubing between and on either side of the bonnet hinges through which the hinge pin could run would fill the gap between bonnet halves and give the whole thing a cleaner look. If the tube were fixed to only one bonnet half (although in theory it might not need to be fixed at all), it would still allow you to open and close the bonnet.