I am preparing to install Harken Track Risers on the cabin of my S-2 27. The risers are mounted on plates that attach to the cabin roof, but there are no backing plates for the interior of the cabin. Is it necessary/advisable to have my local welder design backing plates for that installation? The boom on the S-2 accommodates either end-boom or mid-boom sheeting. Since I am fitting the boat for mid-boom sheeting, do I need more than the one connection to the boom. Is it necessary/advisable to retrofit the boom with blocking at three points instead?