MAD Wiring with Autometer Voltmeter already installed

Thanks for your input. Does this diagram make sense to what you are referring to?

If so, what gauge wire do you feel is best to run from the alternator to the battery? Also, what fuse?

View attachment 1715081693
In that drawing the volt gauge looks to be hot at all times. That would drain the battery. A volt gauge goes on a switched hot.