To you they may not look great. To me they look awesome. The oddities are what makes an authentic trooper.
AP is not the best armour for ANH. Too many of it's ROTJ origins shine through to make a convincing ANH trooper unfortunately. But, if you was to try the brackets, there is no reason why you could not mount the brackets on the face of the armour if there is no return edge. There are no excuses not to use the original strapping on any armour if you want screen accuracy. And if you find an excuse, maybe you have the wrong armour or you do not really want to go the next level of accuracy.
It would be cool to have a new status to achieve, even if it is outside of the 501st. Somewhere mismatched parts or gaffa tape is encouraged. I know it probably is not going to happen but I believe an authentic looking, screen accurate replica should not be perfect looking and go against what most people want. That is fine. Not everyone will want to achieve such a level but I bet there are a few out there that will.