I'll suggest a slightly different tangent - that trying to address boredom through distractions is at best a finite-span solution. There's no toy that'll occupy a dog for several hours. The best you will accomplish is distraction for that initial span when separation anxiety is most likely to manifest.
The real solution to dogs who cause trouble is exercise. A tired dog is a happy dog. Unfortunately with some breeds that can mean quite a lot of walkies. But that really is the root of the problem. If you can manage it, try extending morning walks, or otherwise increase amount of activity. More playing, more running, etc.
We've found a local area doggie daycare once or twice a week works wonders. I've also been investigating cycling with the dog (there are ways of doing this safely, but that's out of scope).
But we definitely notice that less than about 90 minute of walking per day (and ideally 120), and she starts causing trouble. (Can have the odd 'day off' when the weather is bad, but the weekly average is about that.)