You don't have to have an alt that produces enough amperage to completely match your current draw...a 95A alt can likely handle 2k rms or more, as long as you have battery support. Yea you get voltage drops...but to keep voltage at 14+ running 1-2k isn't necessary, its mainly only a problem if you're dropping below 12
1200 rms is getting high for 4 gauge, over that you definitely might as well get 0