I will add a little to this, but the real guy to listen to and learn from is Bill Cody. He is a perch guru. Hopefully he will chime in.
Think hard (more like study) before you change anything. Analyze the current situation. It will be tough without a boat. Usually LMB and YP don't co-habitat in a smaller pond to well. Usually the LMB wipe the perch out, at least any recruitment of perch. They will prey on the smaller perch to well, and then if the large perch are removed, there is no more to keep the chain going.
I would guess you'll want to remove any YP that don't make a good relative weight. See the charts in the archives for the relative weight of YP. Carry a ruler and a scale with you and start keeping records. Which ever size seems to be underperforming would be the ones to cull. However, I don't know what to tell you about the large ones. If some of them are underweight, I am not sure if you should remove them, seeing that they will be the ones to avoid being eaten by the LMB.
Overall, it don't sound to bad of a scenario. If you are catching some YP that are 13", most would be satisfied with that. You might want to create more habitat for the forage fish/crayfish. That's a good investment for long term returns.
