Hi Alex,
Since your flying skills exceed mine it may be absurd for me to give advice, but advice giving is something I am really good at so here I go.
I am choosing a pattern flier as the target of opportunity because they typically really understand how to setup a plane for the best possible performance and they typically are very good RC pilots.
So: if there is a pattern flier in your group that is willing to help you, ask that person to fly your plane for evaluation.
If this person does everything you are trying to do with your plane then ask for instruction.
If the plane is not capable ask for help with setup changes. Setup changes may or may not get you where you want to be.
While I have never really exceeded any of my plane's abilities it sounds like you are very close to getting all there is to have out of your planes.
Good for you.