Rear Cleat access

[Basketcase]

Hello all. On my 77 Sceptre ( I think the SF is the same) the rear cleat does not seem to have access to the underside. I removed the vent, thinking it might be from there, but no dice. It allowed me access to the transom loop nuts, but not up to the cleat. Say you wanted to tighten or even replace these, how is it done?

Thanks!