Chop up the scraped out insides and place them in a mixing bowl. Using a paper towel, soak up any extra juices from the pickle boats and chopped inside pieces.
Thoroughly drain tuna and add to bowl. Break up large chunks with a fork. Add mayonnaise, red onion, chopped pickle, and sweetener. Mix well to form the tuna salad. Spoon tuna salad into each pickle boat. Chill first or serve immediately.
"These tuna pickle boats travel well especially after they’ve been chilled for a bit. The tuna salad tends to stick to the pickles after these have been in the fridge for awhile."