Need Help/Suggestions (GSD and non-GSD)

I have three dogs - see my signature for details on each. Casey was rescued from a shelter last fall originally as a foster but I have decided to keep her. At the time I had another foster (Bindi) and all of the dogs got along okay. After Bindi left I realized that she had been running interference between Casey and Gunner. Gunner has since gone after Casey a couple of times, one incident resulting in several stitches in her leg. Since then I have kept Casey separated from the other dogs since she and Gunner do not get along at all and Charley also seems annoyed by her and shows it by growling, won't play with her, etc.

The problem is Casey seems quite unhappy with this situation. I rotate the dogs between crates, inside time, outside time, and basement. The most interaction and supervision obviously occurs during inside time. If Casey is in her crate, she cries and howls; if she is outside, she's okay for a while and then cries and howls; if she's in the basement, she gets in to whatever she can get to; if she is in the house with me, she tries (and has succeeded) in jumping over the gates to go after the cats (that stay upstairs). She is obviously lonely and craving for more attention than she is getting. She desperately wants to play with the boys but I have tried very closely supervised playtime with all of them together and Charley is not interested and Gunner only shows aggression toward her.

I cannot get another dog to keep Casey company during her rotations. Any ideas on what I CAN do to make her "alone" time more bearable? I am including a sample rotation schedule below. Note that I cannot have crate and inside time at the same time as the crates are in the living space and the dogs will bark and cry if one is out and the others aren't. So when they're not in their crates, there is always one group of dogs (either Casey or Gunner and Charley) who are unsupervised. The boys usually behave pretty well and could even be left out when I am not home or at night if it were not for the fact that Casey would bark/whine from her crate. Also, if the dogs start barking outside they are brought inside immediately and this also causes a shift in the rotations. Walks are typically done in the morning, weather-permitting, and would also result in a shift of the rotations.

7:30 am - dogs fed
7:40 am - Gunner and Charley outside for potty
8:00 am - Gunner and Charley to basement (while kids eat breakfast, get ready for school) and Casey outside for potty
8:20 am - all dogs in crates while I take kids to school
8:40 am - 12 pm - all dogs rotated between outside, inside, and basement
12 pm - 2 pm - all dogs crated for afternoon "nap" (this is the time period I typically use for my lunch, gym, errands, etc.)
2 pm - 3 pm - all dogs rotated between outside (for potty), inside, and basement
3 pm - 4 pm - all dogs crated while I pick up kids from school and kids do homework/have snack
4 pm - 10 pm - all dogs rotated between outside, inside, and basement
10 pm - all dogs crated for night

I want to be fair to all the dogs and keep them happy - need help with suggestions for poor Casey!!