My 2 cents is get double 00 gage wire. Get that and do it once and be done.
When I was a Kid I had that issue and along with every little ground wire it melted he copper oil pressure gauge line right at the gauge spraying my legs and feet with engine oil.... Fun Fun FunAs Blackduck said ground to the motor. I see this mistake all the time. You ground the frame off the motor. Do not ground the battery to frame and then ground frame to motor. Some people think it’s the same. It doesn’t matter if all the cables are big. It’s not the same.
The reason why is a failure of the motor to frame cable. In one case, the motor starts and you wonder why some things don’t work right. (Lights, instruments and radio) In the second case, when you hit the starter, you will fry all other paths to ground from motor to frame. I’ve seen a throttle cable melt.
Your Right, that is how they do it on commercial equipment !Seems like I recollect that the ground schematic shows battery to engine block and then block to the frame.