I had the yard do it. What they did was to just leave all the existing cables
in place,in the galley
floor, and run a new cable (+ & -) from the new location to the old series. Basicly just extending the current
setup to the "under the bunk" location. They also "glassed in" battery boxes, under the bunk, for stability. Solid as a rock!. Let me know if you have qny more questions? You are a new owner, aren't you. I have had my "Island Time" for 3 years, so may be able to answer several questions for you.
You can write me direct at "email@example.com", if you like.