I would not reccommend having the dogs left in the yard. It is too risky. You may end up in a situation you do not want to be in. Even though you will have lots of toys to play with, what happens when both dogs want the same toy and no adult is there to supervise? What if someone enters your fence? No fence is an absolute safety zone. Kids always find a way to climb it, especially if they know there are doggies behind the fence they can “play with”. IMO I would crate them when away and make sure they get a lot of playtime/exercise when you are home. Maybe you can hire a dog walker you trust to come in and walk the dogs. It’s better to be safe then sorry.