First, you have to fish a lake with big muskies. If bigger fish are you’re only goal sometimes you have to change water to achieve your goals. Check for lakes with good track records and more specifically certain times of year when big fish seem to get caught. Every water has its own makeup.
On the water you describe, or on any water for that matter … in general, concentrate on deeper lake sections to find big fish. There are always exceptions, and I’m certain there are times of the year that big fish will be in the shallow section. But bigger fish tend to live in the deep stuff, and shallow structure with deep water adjacent generally has more big fish potential than spots without deep water access.
Casting works certainly, but even though I don’t prefer it, I do believe that trolling in deeper water is simply a better big fish method. You won’t necessarily catch more fish, but per hour on the water I believe more trophy class fish will be taken trolling as compared to casting methods.