Feeding BG is, I suspect, one key to growing trophy LMB. Additional forage weight & numbers, plus it draws out prey into the open. Also, raising additional forage in a small pond dedicated to that purpose can be helpful.
During winter, rainbow trout can help feed LMB. They are easier for LMB to swallow than TP or BG due to fusiform shape. One issue I ran into last winter was stocking 100 pounds of both larger (10-12 inch) RBT and smaller (4-6 inch) ones. The big ones grow extremely fast on a feeding program and within six weeks are too big for almost all bass. This year I'll stock 2 to 3 times more smaller RBT than bigguns. Bigguns are great fun to catch during cold months (cold being any temp below 55F where I live), but smaller ones do more good for LMB.
Freshwater prawns could be interesting, especially if they could be raised with a fish that didn't eat them much. TP may fit the bill. Wonder if large prawns might even be grown with smaller BG that couldn't swallow them. Or would BG attack the poor crustaceans anyway?