Glad to hear you are spending some time in the western end of the Island!
A couple great restaurants that are similar to the Lobster Barn are The Catch Kitchen and Bar and The Boatshop Restaurant. Both of these restaurants have delicious food and are both situated on the water just like the Lobster Barn
The Catch is located in West Point right on the harbour next to one of our provincial park beaches. They have a great variety of seafood and non-seafood options. A personal favourite of mine is the lobster roll and their potato salad, I'm drooling just thinking about them!
As for The Boatshop, it is situated on the harbour at Northport (very close to Alberton). This is an absolutely stunning location right on the water overlooking the boats but also the sandhills as well. A fun fact about the boat shop is that the restaurant is in a building that they use to use for shipbuilding back in the day.
Hope you enjoy one of these suggestions if not both!