Another annoying Alternator question

[seik5]

New engine has a 12SI 100 amp 1 wire internally regulated alt. upgrade. New stock engine harness alt. hot wire appears to be too small considering I will have dual fans added. Also have Volt gauge in new elec. gauge cluster. I am thinking all I need to do is add a 6 gauge fused wire battery to alt. Since I have no warning light or amp meter I would not use any other wires. I have not done this before and have zero confidence in my thought process. I just can't find a schematic that covers my situation. Help?