Using an alternator to feed your house batteries?

sure you can
your going to need multiple strands of "2 aught" cable or maybe something larger
unless you fuse the cables near the alternator, for the max rating, of the smaller cable run

issue number one will be power you rob from the engine to drive this humongous load your thinking about, the strain on the belts and the additional load the engine cooling system and pulleys

nothing that can't be solved, IF you throw enough money into all the heavy duty OTR parts needed for the job