I thought I would share some of the photos on my moving the exhaust outboard of the stringers to make room for fish boxes. Special thanks to Marlin and JP for 1) telling me this is how I should do it, and 2) giving me the step by step that Capt Patrick gave Marlin on Wahoo.
Here's essentially the starting point. Old 5" exhaust replaced with 6" exhaust:
Old exhaust is patched:
Capt Patrick's Vermiculite & epoxy filler packed in all the spaces and shaped about the new fiberglass exhaust tube:
Vermiculite before & after faired into shape:

1708 Added:
Here's the exhaust run, new rudder shelf, and test fit of the new deck I built from Coosa showing the space that was created by moving the exhaust outboard:
Gelcoat rolled & sanded:


A few minor fixes to take care of before I tape off and roll out the bottom paint, but I'm very happy with the results. None of this would have been possible without this website and the help from The Faithful walking me through how to move the exhaust. I sincerely appreciate all the help I have gotten along the way.
Thanks,
JohnV8r