Re: Chain plate or impact.
Take them out from the inside - don't even THINK about going through the outside. Remove them intact and take them to a machine shop that does stainless - they can simply cut new ones from bar stock and use yours as a template for any drilling.
Sand and polish the new ones then get them electropolished - they will outlast you.
The simplest install would be to drill through from outside the hull and mount them in their original places inside the hull (after grinding those areas smooth).
I, myself, personally intend to continue being outspoken and opinionated, intolerant of all fanatics, fools and ignoramuses, deeply suspicious of all those who have "found the answer" and on my bad days, downright rude.