Loving the game so far.
However, the classic interpretation of sneaking in D&D involves the amount of noise made. Not just if one is within a cone of vision from another creature during the attempt. Four paladins wearing medium and heavy armor should not have a very high likihood of sneaking up behind anyone due to the noise they are making. I think adding a mechanic based on distance and sneaking proficiency, independant of being in line of sight, should be added.
