2006 supra 21v launch

I need a little help here. Me and 5 of my buddies are going up to lake Trinity in about 2 weeks for a week cabin trip. we're taking my friends 21v supra. we want to take my RZ2 but my parents shot that plan down. his boat has the ballast from the factory which is like 1000 pounds or somewhere around that. when we're boarding there will be full ballast and 9 people in the boat. last time i rode behind the boat it seemed like it was a bit of a struggle to ride at 75 feet back doing about 23.8. in an article that i saw in a mag it said that the sweet spot on that boat is at about 65 feet. what are those of you that ride behind this boat riding at.