If you recall there is no way on earth a bad battery can consume inapprpriate levels of amperage without getting hot - ain't gonna happen.
You are relying on a single (?) Or multiple AGM batteries for how many amp hours of nightly duty?
Doubling of wire = 3 steps down in gage. 7-6-5. So your equivalence is 5-gauge. So ampacity is not a question. But measure volt drop between the altetnator output stud and house battery lead post and steel yourself for a shock.
With that alternator your headlights wiper and heater on high should slam 70+ amps into multiple AGM house batteries. Daylight should see close to 100 amperes potential. Your charge path is defective.