My plane is a lazy high wing floater with 5 foot wingspan. It has a brushless motor that can handle 35 amps continuous or 50 amps burst current. It has a 5-cell lipo. The largest diameter prop I can put on this plane is 13 inch. What I've been doing is to limit the current to 35 amps by setting the upper throttle endpoint lower than 100% so that I won't accidently over throttle it during flight. I've been very pleased with this setup, but I don't know if this is the most efficient combination.

I've heard to put the largest diameter prop the plane can handle considering ground clearance for the best efficiency but what about pitch?

If I change from a 13.6.5E to a 13x8E will the decrease in RPM while maintaning 35 amps be more efficient without loss of thrust for my lazy high wing floater? I don't fly this thing at full throttle all the time. All it takes is about half throttle to keep it flying comfortably.