Dual alternators, as in using one for the jeep normal alt. function, and a second that is unregulated for welding that you only use to weld is one idea...it sounds as though some are suggesting 3 alternators, though...one for normal,and 2 for welding. I agree with dirtrod...the idea is backwoods usage, and simplicity. Save the hyper-welding for home, where you have all the right rods, tools, etc. Keep the jeep welder a functional usable tool, but don't try to make it a space-shuttle.
2 alternators is simpler (wiring wise) than 1 used for both alternator and welder. 3 alternators would be a nightmare.
Moneyless, Will weld for jeep accessories.