From what I've been reading tonight, the PBY could carry 4000lbs of ord. Bombs, depth charges and torpedoes. Forward guns as well as waist guns. The Black Cats alone sank over 112,000 tons of shipping.
Yes, I do agree now that the resupply thing is a bit far fetched, but surely HTC can find something for her to do. The PBY is too important not to be included in the plane set.