I made some a few years ago for Insane boats that were .125 thick, 1.25 wide. I was out of boating then so I have no idea how they did or did not work.
If Jerry won't make rudder like you want, I will. And I use 7075 as well. I won't make a rudder out of 6061.
I was in the boat hardware business 6 or 7 years ago when a health issue forced me to quit and sell my shop. Well, I'm healthy again and I'm back making hardware.
I'll make ANYTHING you need for your boats. I may be a little on the slow side, but I always get it done.
I'm not as fast as I once was, but I'm as fast once as I ever was.