Whisk together first five ingredients in a medium sized bowl. Season with salt and pepper to taste. Add crab and shrimp and toss to coat. Cover and refrigerate while you prepare the vegetables.
Combine all the hand-chopped vegetables in a large bowl. Remove about ¼ of the vegetables and put in a food processor fitted with the chopping blade. Pulse a few times to get a finer chop and then return vegetables to the hand-chopped vegetable bowl. Add shrimp/crab mixture to vegetables and toss.
Gradually add V-8 juice. Start with 1 cup and then add in 1/4 cup increments until you like the consistency. Add salt and pepper to taste. Chill for several hours before serving.
Serve in pre-chilled individual glass bowls. Garnish with diced avocado, croutons and lime or lemon wedges. Drizzle with a great olive oil and pass tabasco or Sriracha sauce to individualize the heat.