I had most of the boat apart, and I know the holes you're referring to. I can tell you this - up in the bow, there's a large conduit that runs up to the front of the bow, and the wiring for the bow light comes up through it, I assume from the console. I also know that this same conduit exits out the stern, bottom of the transom. I ran a fish tape from the bow down into that conduit. When it gets to a certain point just around where the upper deck drops to the lower deck, the fish tape drops and it won't follow through to the stern, so that conduit branches off, and there's no way to get to it since it's under all the foam that the boat is packed with.
There's also a way to get the wire in the gunnel (if you feel back by the stern where the gunnel meets, it's open there. However, I would have to expose the wire from the bow compartment to get it up in the gunnel, though I guess I could do that in the very front of the bow in the storage compartment. Seems difficult. I had every piece of floor up and couldn't find a way back there.
I believe the onboard charger would need to be directly connected to the cranking battery, so I can't connect to the leads at the fuse box.
Wiring up my trolling motor battery was simple - just would love to be able to use the second bank of the charger to hit the cranking battery.
If you come up with anything, let me know -
FYI when you pull the flooring up, some panels are difficult to get back in - takes a lot of fooling around to get everything back together. Also I noticed when doing this that some of the screws holding my seat bases were stripped so I fixed those while I was at it. So much for quality control!