For my 1978 Oday 20, I am routing halyards to the cockpit using a lifting block, deck organizer, and line clutch. How do I "back" the through bolts on the inside of the cabin? There will be 12 through bolts. Will fender washers provide enough support or is there a better solution? Is the headliner an issue? There is no way to remove the headliner. Can I put the fender washers directly against the headliner without crushing, cracking, or punching through it.