Before I get started I just want to give a recommendation. Whenever you are putting hardware into a boat, make sure to use stainless steel hardware. You may pay a little extra for them but your money will be well spent. You won't have to worry about rusted bolts in five years when you go to change out something. I buy them in bulk and save all the extra stuff that comes with new products I order.

Tonight started with the battery compartment. The main battery was too small. In this picture you will see the original configuration.

Take note of the wire tunnel in the right corner of the photo.
Because I was putting in a size 30 battery, I needed to reconfigure the layout. I removed the old battery box and then removed the wire tunnel cover. This boat has alot of rivets and I drilled them out. Because the layout changed, I had to rethink the mounting of my charger. I mounted it on the bulkhead, scribbed the wire tunnel cover, cut it with a dremmel, and installed with stainless screws. I then put the new batter tray and battery in.

When making my wire connections for my charger extension, I always utilize shrink tubing. I then overkill it buy taping the ends.

After both sets of extensions were done, I attached to my fish tape and pulled them through to the trolling motor battery compartment. I terminated the ends with the required inline fuses, wrapped the wires in a protective casing, and installed in the battery boxes.
I have OCD "Obsessive Crappie Disorder"