I think rainbow trout being stocked into a lake does create a huge boom for larger LMB as a food source.

One lake I fish in western MD has crystal clear water and has had many bass over 10 pounds caught out of it. Not a common thing in that area of the state or the mid Atlantic area in general. They generally only stock rainbow trout in the 9" plus range into the lake with most being 12" and above. It takes a fairly decent size bass to begin preying on a 9" rainbow and especially a 12" rainbow trout. Those trout are dumper than a newly stocked FHM from a fish farm. Full of lipids, high energy bass feed. The lake is also 88 feet deep at it's deepest spot and because of this depth and water quality, is able to support trout year round. Just like many of the California lakes that produce huge bass are "two story" fisheries. The upper story supports the warm water fish like LMB. The lower story, where the thermocline is supports the trout.