i have Power Premire and have alternator problems, on my 2nd one and now I have to carry a rebuilt. If you drive in dust it likely will quit.
IMHO get the battery powered hobart, don't go down the road of rewiring and new alternator.
I am not a happy customer and tell you the product is a bad POS. My message to them
you must have crappy luck then, the one on my old 06 TJ is daily drivin by a truck driver that bought it from me that works for me and it hasn't failed yet not even a regulator issue and he wheels the piss out of it...
I carry a Ready Welder, MIG (flux or gas) welding from a portable unit. Works very well, single pass 1/2", and as it's portable all you need is a couple of batteries to get it to work.
I keep a ready welder right now and it works great, its just my batteries are a pain in the butt to get out and it seems like i'm always welding on toyota's I thought it would be bitchen to be able to run the gun off of the power welder for the ultimate setup