I can't answer your stocking rate question. What I can comment is that my stocked hybrids are staying on the feeders. These went in about mid May. I like to throw a cast net on fish busting the feed and usually I'll get several HSB in the nets. There are shiners, LMBs, and bluegills on the feeders too of course.
Now my pond is only two years old (8 acres w/ 3 feeders) so the LMBs are nearing a 13-14" average size while the hybrids are 6 to 7" avg size so maybe just out of the LMB's reach.
Just thinking that in your situation the hybrids might be easier prey if drawn to the lone feeder, where likely some LMB are hanging out.
