I have a 19 mondo and can surf it no problem. I have the 750's in the back and 500lbs of lead. I a guessing its your board or where you are trying to surf. I am 6' 200lbs and like i said, no issues without a rope for as long as i want to ride.

Try this setup, 100 ballast on surf side, 80% on non surf side and only 70% in front. Make sure your wake plate is up at 20% or less while underway and try to stay closer to the middle behind the boat not way out to the side.