I've got a couple guys from the Club coming over to the boathouse on Sunday. We are bringing the sewer camera and will begin there. If satisfactory visual confirmation can be obtained and I feel confident of the condition, then I will leave it at that. If we cannot get a decent view, then we are prepared to remove the connectors and replace.
I really believe that the critter had just begun to make its nest and had contained itself abaft of the engine room bulkhead. My reasoning for this is the connector just inside the engine room compartment had loose hose clamps most likely caused by back pressure. In that case, the connector adjacent to the water tank is the most likely one to have been damaged, if any.
I will do some research on the mufflers you mentioned and will report back on the findings of Sunday's surgery.