I agree with you concerning using the body as a ground. But I take it an extra step. There is so much about the Tesla that we do not know reference when grounded wires at still carrying current. Loosening an existing ground (screw/bolt/nut to slide another ground terminal into the group could cause the spark of electricity to jump. I've seen it, when the car had not sit long enough to turn itself completely off. When I am making a ground on my Tesla, I drill a new hole in a metal internal panel and use a self-threading screw to get a new contact to the body. I'm not going to debate someone if it necessary or practical or even a safe guard. I take care not to drill though something that's going to puncture a hose, wire or harness. If I can't get to the backside to find what I am going to hit, then I find another spot to drill. This simply in my opinion is going to lessen the risk. And on the 12v positive side, I add another inline fuse to safe guard the device.
Good point on active circuits and removing their grounds.
With these new holes, are you using stainless steel screws or something else to prevent galvanic corrosion down the road? (Assuming even interior panels get the sea breeze salt exposure)