Wow, So many popular misconceptions I don't know where to start. Before I jumped off the rat race boat and joined the Sheriff's Dept, I was an EE in real life. I inspected wire and cables at NASA, thus the link to our wiring guide.
You can do no harm by going to larger wire, it can not create a voltage drop, ever. Bad connections can, but not larger wire.
That leads to this, NEVER EVER solder a crimped connection, the wire will break at the solder to wire joint due to vibration.
The 8 ga is 8 ga statement is correct. The finer the strands, the more flexible the wire is which is fine for exposed wire that may be subject to movement and such. THHN Stranded electrical wire you get from Home Depot is stiffer and perfect for snaking from front to back of our boats. We used it in all areas that were not exposed to the temperature extremes of the orbital environment, namely in interior flight crew space. STS-37 to STS-105
Radio waves travel on the skin of a conductor, raw current uses the whole wire.
Sorry if I stepped on toes, but after a career of wire safety, I am sort of a fanatic.
There is another whole subject about amp-hours and the way batteries work, but what the hell, if you can't troll all day, you need bigger batteries.