Eddie, I’ve found 5200 RPMs to be a good static ground setting for best cruise. Like you said, anything much higher and cruise suffers slightly. When on those long cross country flights, an extra 10 mph helps a little. Take offs suffer slightly but I’m usually operating off longer hard surface runways so achieving the shortest distance take offs is rarely needed. Even when I was flying in Idaho back country strips with my model 4 with the same prop and engine, the same prop settings worked well but most times I was solo.
In- flight adjustability would be better but Light Sport yet does not allow this but who knows, maybe someday down the road the FAA will wise up and allow those props.