#1, as long as the battery is out of the system, that is fine.

#2, this is probably the cheapest and easiest option. Your version B won't actually disconnect the electrical system since the ground is still connected to the body.

https://www.amazon.com/Side-Battery-Master-Disconnect-Switch/dp/B001N72FES

'18 Ford Raptor, random motorcycles, 1968 Plymouth Fury III - 11.37 @ 118