I got two warm days in a row so I made some progress.
Using West 105/205 and 405 as structual filler I laid in filler in the center slot where there used to be an air gap that became a water gap.
Keep in mind that the on old plates which were flat the only portion of the plate that touched the hull was the bottom 1/4 of an inch. What I need to do is build out a 'landing' for the new plates that will fit the curve of the hull and be flat at the plate.
This is step one, in progress. Do some fill, then do some seal, then overcoat, and overcoat etc..