As this project is coming down to the wire I keep encountering little problems that are incredibly frustrating!

I am installing the rudder controls on my double, I carefully drilled the holes and now as I am putting the aluminum rudder controls in the boat I find that on one side the holes are the slightest bit off and I cannot get the screw to thread into the rail. I take my drill (aaaahh!) and make the hole a little bit bigger to allow room for the screw to move to the hole on the rail. I finally get the thing to thread and the rail onto the hull, but now I have a hole that is bigger than my screw, (the shaft, not the head) and the rubber O ring gets sucked into the boat. Any suggestions on a fix for this problem? A bigger O ring, silicone? Do I need to try and fill the hole with epoxy and redrill?

Thanks, Tom