Apollo 1" Bronze thru-Hull Fitting, 5-3/8" Max. Hull Thickness at West Marine, SKU#1841055, $53.
I don't know of any 1" stainless fittings that will fit a 4" thick hull. I DO know that you can get your local welder to lengthen a shorter one by combining two, to make the custom length, but it will be $$$.
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Common Sense is learning from your mistakes. Wisdom is learning from the other guy's mistakes.
Fr. Frank says:
Jesus liked fishing, too. He even walked on water to get to the boat!
Currently without a SeaCraft 
(2) Pompano 12' fishing kayaks
'73 Cobia 18' prototype "Casting Skiff", 70hp Mercury
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