MikeAqua: Good idea for weight distribution. For the heavy leads for you trolling motor ... when you know where you will mount the circuit breaker (some shelter is best) ...
Have an auto electrician make up and terminate any heavy duty cables. You are looking for tinned cable and a gasless crimp which is usually a hex or radial crimp. Not soldered and not a punch crimp. You then want adhesive heath shrink over top of the terminal and a few inches of the cable.
What is the thinking behind not soldering the cables? Reason I ask, Is that in my van. The alternator output was wired to a double crimp terminal on the starter motor, and from there to the battery. The alternator output current made the terminal get really hot, which then melted the plastic end cap on the starter solenoid, the B+ terminal then started migrating through the molten plastic. I was very lucky that it didn't touch the metal sides of the solenoid housing. Otherwise I would have had a direct short through the starter cables.
All because that connection wasn't soldered after it was crimped. Alternator is rated at 120A so even 0.1ohm can cause excessive heating at that current. And trigger thermal runaway. The other end of the alternator cable is soldered as well as crimped.