I'm sorry you find yourself in this situation.
I'm sure others will have good suggestions about working with reactive dogs, but my first thought is that you need to find ways to exercise/engage the dogs that fit in with your interests and your schedule. Three hours per day of dog walking, if you wouldn't normally be walking for enjoyment/exercise, is nuts. There are lots of types of mental and physical exercise that tire out a dog more quickly. My poodle could run/walk all day, but a half-hour of swimming, for example, sends him into a dog coma for the next ten hours. You might try activities like trick training or scent work, both of which can have the added advantage of helping the dog learn to focus on tasks and on the handler, which can help with managing reactivity. Fifteen minutes of trick training tires a dog out more than any amount of walking/running, in my experience, and they actually learned something from it. (Google "do more with your dog" for more on teaching tricks.) Don't deprive yourself of hiking and going to the beach - just bring your girl and enjoy yourself. Give the boy an extra game of fetch or whatever when you get home.
I hate to say it, because no one likes to hear this kind of thing, but..."sliver lab" should have been a warning sign. Obviously this is not your boy's fault - he's the victim of this scam, too. There are few to no ethical breeders of "sliver" labs because it requires a)inbreeding and b)they're probably the result of breeders lying to the AKC about parentage. You're not getting the creme de la Labrador creme when you get a silver dog, generally speaking...you're getting dogs that were bred for a cash grab, not for the love of dogs or to improve the breed. In future if you want a pup, I'd do some research into how to choose a good breeder that is producing healthy, stable dogs. (What I'd REALLY suggest is just adopting a nice adult dog that already had the temperament and characteristics you want, rather than gambling on a pup at all, but hey, people love puppies.) That ship has sailed now, obviously, but just for future reference, or for any lurkers who happen to be reading this.
I'm sure others will have good suggestions about working with reactive dogs, but my first thought is that you need to find ways to exercise/engage the dogs that fit in with your interests and your schedule. Three hours per day of dog walking, if you wouldn't normally be walking for enjoyment/exercise, is nuts. There are lots of types of mental and physical exercise that tire out a dog more quickly. My poodle could run/walk all day, but a half-hour of swimming, for example, sends him into a dog coma for the next ten hours. You might try activities like trick training or scent work, both of which can have the added advantage of helping the dog learn to focus on tasks and on the handler, which can help with managing reactivity. Fifteen minutes of trick training tires a dog out more than any amount of walking/running, in my experience, and they actually learned something from it. (Google "do more with your dog" for more on teaching tricks.) Don't deprive yourself of hiking and going to the beach - just bring your girl and enjoy yourself. Give the boy an extra game of fetch or whatever when you get home.
I hate to say it, because no one likes to hear this kind of thing, but..."sliver lab" should have been a warning sign. Obviously this is not your boy's fault - he's the victim of this scam, too. There are few to no ethical breeders of "sliver" labs because it requires a)inbreeding and b)they're probably the result of breeders lying to the AKC about parentage. You're not getting the creme de la Labrador creme when you get a silver dog, generally speaking...you're getting dogs that were bred for a cash grab, not for the love of dogs or to improve the breed. In future if you want a pup, I'd do some research into how to choose a good breeder that is producing healthy, stable dogs. (What I'd REALLY suggest is just adopting a nice adult dog that already had the temperament and characteristics you want, rather than gambling on a pup at all, but hey, people love puppies.) That ship has sailed now, obviously, but just for future reference, or for any lurkers who happen to be reading this.