Can use a pic of those corner caps I believe you are jonesing for,if they're what I'm thinking of, you could just get some aluminum plate stock,cut out the pattern you want, I love to over-engineer at this point for something like per say...
"Hmmm I need to find this piece of crap to hold my boat together

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wait a second,,, I'm a fisherman:, that in itself makes me- a carpenter,engineer,mechanic,seamstress,plumber,pip e fitter,machinist,fabricator,etc...! So you make your own plate but make the top big enough to mount something cool to it, you could even use plate like 1/2'' double on top and core through for some sturdy as hell rod holders,cleat location....and so on..."
point being...sometimes a good mind of a fisherman some aluminum and a good welder go better than oem replacement type stuff, just sayin, good luck!