I suggest you get professional help. It is extremely hard to give good advice on a big water with lots of species absent sound data. My guess is those LMB pictured are not spawning but are hunting the warming shallows.

Lots of PB posters will try to help but only you can make the decision. IMO you should not make any major choice without pro help on a water like this. Everything I have read so far sounds like you have a predator heavy lake that has low productivity. If so, you can make changes based on goals (every goal is not sound for every lake) but the goal should be determined after you have good info and a reasonable list of goals that are lake appropriate. IMO that requires an eyes on examination buy a pro with experience with lakes like yours.

All the rest is just guys like us (all posters above) with limited info shooting in the dark to try and help you out.