Hi, not a I-28 owner but this construction is first class.
The plate distributes the keel force more evenly and properly bedded would be a great improvment on the single heavy washers on my Westerly.
I have been thinking along these lines for a permenant cure to seepage into the bilges due to keel/hull flexing.
Can only link pairs of keel bolts at present due to bilg strengthening struts but it may be worth removing these as they require repair anyway.
I would be concerned about the amount of corrision visible on your keel bolts and nuts. It could be worse were it can,t be seen.
The great appear great because you are on your knees. James Larkin, Irish Labour Movement.