Bacon Tuna Boats

I want to throw a party this weekend, just so I can make these! 

10 oz tuna fish
1/2 cup cooked, chopped bacon (or faux bacon)
2 scallions, thinly sliced (roughly 1/3 cup when sliced)
1/4 cup chopped fresh flat-leaf parsley
1 rib celery, small dice (roughly a half cup)
1 tsp Mrs. Dash Original Seasoning Blend
1 ripe avocado
squeeze of fresh lemon juice (about a teaspoon)
a few grinds of black pepper, to taste
2 English cucumbers