The idea of the 2nd dog is a good one but, you still need to spend more time with them, My first dog a yellow female Lab was a holy terror while she was buy herself. She got into everything, we have 5 acres and the dogs have access to 2-1/2 enclosed by the invisible style fencing, so it was not that she could not run and investigate, it was that she was alone and could not stand it so she became highly destructive. She ate the phone cord off the house, chewed everything in sight, tore up every item that we attempted to use a "bed" for her. After we had her bred and kept a puppy, she was an entire different animal, she actually would scold the pup for things he was doing wrong, digging in the yard etc. What we found is that while she was pregnant, and afterwards with the pup we as a family spent much more time with the dogs, and they became better behaving animals all around. We now 3, 100 lb dogs and they are honestly the best behaved animals we have ever had, the entire secret is time, the more you put in, the better it is going to get. As for the barking and whining I went thru this as well and every time she barked we had a discussion and I made it know to her that we were not doing that, If she continued I let her out and went with her to verify nothing was there and she had no reason to bark. I did not want to stop the warning barks if someone or something was present, my female did find and rescue our 3rd dog as he was dropped off in the road. in sub zero weather and without her warning he surely would have frozen to death.
I know its hard to find the time but in the end you will have a great companion, just keep working, positively correct behaviors you dont want from the dog, and praise and reward every thing she does right. It does not have to be a dog biscuit every time, I give Ice cubes, cheese, apple, etc for treats, and many times I make them repeat the good behavior for the treat.