One problem (of many) with this idea: the only thing a rescue "saves" is a statistical death, and that's not certain. PBYs were not particularly survivable if engaged, as they ceratinly will be in MA. Likely result : death for rescuer and rescue- ee.
And IF the PBY pilot were guaranteed a safe return, who would fly? The time a rescue would take wouldnt be owrht it to most every body, esp to those who play for score (and would presumably care about the statistical column change).
And lastly, in the briuef list that flies off my head, if you are not in the plane, you still have a "D" in the KPD column. All the rescue would do is change your perk fractional multiplier.