Weight & wheel alignment are important!
I can't comment on how to adjust toe-in on the trailer. I think it's pretty well fixed when the spindles are welded to the axle. Unless the axle tube is bent, I think you are sort of stuck with weight distribuition. Or....Have you measured the ball weight? You can use the bathroom scale trick directly or with a support block on one side to divide the weight in half.Are you towing level? The trailer should be level under tow. Use an offset receiver to bring it level if it's not already.Is your vehicle up to the task? (follow what the Mfg says, not what a friend or someone in your boat club says).Is your hitch appropriate?Are the trailer & tow vehicle tires at the right pressure?Are the trailer wheel bearings greased & adjusted right?Do you have brakes? (you should with that size boat) are they adjusted right?Finally, if you do need to have more weight on the ball, you may want to move the boat forward on the trailer, if at all possible. The ball weight should be between 8-12% of the trailer weight for best results.The prior owner of my Laguna 18 had a 3" thick chunk of plywood U-bolted to the trailer winch upright and that's where he mounted the outboard when towing. It did tend to crack the outboard bracket a bit, but it made the ball weight correct. I took it off the front and put it on the floor of the cabin, and it was still OK. Then, one time for a week long trip I loaded the cockpit with heavy ice chests, BBQs and food boxes and nearly lost everything when the trailer started to sway REAL bad going down a hill on the freeway. I was sure it was going to flip the car and put a big dent in our vacation plans. I slowed down, got it under control and went back and cramed everything into the cabin. That solved the problem.Good luck!