Not to derail your thread but I'll give it a shot.
Why do you want a larger alternator? I too have looked at larger alternators (and besides Mean Green $400 there are one or two other options but similar prices for the same output.)
How many amps do you want, and how many do you think you need?
With a good battery and stock alternator you'll be able to recharge your battery after not too long. I ran dual deep cycle batteries for a long time and never had a problem charging them with the stock alternator.
Coming from someone who uses a winch, has eight 55watt lights on at times (2 headlight, 2fog light, 4 rock lights) and occasionally a 1000 watt RMS amp pounding toons in the back, I'd say I put the stock alternator to the test.
Just trying to save you a few bucks you may not need to spend. But if you are