Fill large bowl with ice and cover with water. Bring a large pot of water to a boil over medium-high heat. Gently lower eggs into water being careful not to let the eggs crack. Boil for exactly 12 minutes then plunge eggs into ice bath. Let sit until cold, 15 minutes. Remove from water and chill until ready to make the filling.
Peel eggs. Wet a clean kitchen towel with warm water, it should be pretty damp. Wet the blade of your knife and slice one egg lengthwise through the center in one continuous motion (don’t saw the egg!). Use the towel to clean the blade and wet the knife and repeat with remaining eggs, cleaning the blade after each cut.
Scoop out yolks and transfer to a food processor. Process yolks, mayonnaise, horseradish, Dijon, 3/4 teaspoons salt and 2-3 Tbsp water until smooth, light and creamy. It should be the consistency of cake frosting. Scrape into a large pastry bag or gallon sized zip-top freezer bag and chill until ready to serve.
Fold crab, oil, parsley, lemon juice, lemon zest, and 1/2 teaspoons salt in a medium bowl until completely combined. Cover and chill until ready to serve.
Cook bacon in a large skillet over medium-high heat, stirring occasionally, until deep golden brown and crispy, 7-10 minutes. Transfer to a paper towel lined plate and let cool.
When ready to serve, cut a 1/3” wide tip off the pastry bag or the corner of freezer bag. Pipe into egg whites. Serve with crab salad, bacon, dill, tarragon, chives, pimentos, capers, and serranos.