Not much of an advice guy, but here are a few of my initial thoughts based on raising thousands of CNBG in a 1/4 acre pond here in Hooterville.
FLX asked the first question I would have asked. How are you going to get them out? At the volume you're wanting, cast nets alone won't do it. Since your pond is a production pond, and not a recreational pond, getting those fish out when they're the size you want is very important. I use a commercial seine net here, but that's not required. More inexpensive nets are available, and when I used them, I'd just zip tie smaller nets together. Ewest has some great info on partial seines, and I would follow his advice if he sees this thread.
If you're targeting the 5" BG for fish food size, then you're probably not feeding the smaller BG enough. BG can get very aggressive, and many times the smaller BG won't readily feed with the larger BG. I would start feeding a mix of the smaller Optimal you started with, and the current size you're using. I do this on one of my big puddle feeders, and everybody shows up to eat. I hand feed my CNBG in my hatchery pond, but I use the same technique. The small 2.2mm pellets I throw are eatten at a near 8-1 ratio to the 3/16" pellets. The 1/8" pellets are eaten at a 4/1 ratio. That lets me know exactly what size class of CNBG are eating. The larger BG will almost always target the larger food first, and mixing food size gives the smaller BG a chance to eat and grow.
Adding another feeder in a different location would probably be more productive than just extending the single feeder's throw time. Pond's without cover are like roulette wheels, in that fish will roam until they find a favorable spot to stop. Feeders do create that spot.
I always assume there's predators in an uncontrolled pond, so the actual numbers you stocked may now be lower than expected. GSF will also really hurt BG fry, and it sounds like you may have a large number of those also.
Last thing is to know the size of your predators that'll be dining on the BG once they're moved. I would think 6-8" is a good target for breeders, but you'll probably need to remove a good number of smaller BG also. If not, the biomass numbers could get be a problem, and you're more likely to get a bunch of stunted BG. If available, I'd stock those in the fishing ponds that have the most hard cover. If the cover is vegetation based, then it all goes away when the water cools off, and those smaller fish probably won't last through winter. That's not a bad thing, it's just a thing.
Just my thoughts about how I'd proceed.
Hopefully the smarter guys will chime in, and please keep us undated about how you handle this. We'll all learn from you.
