Why propane? At least 50% of the justification for buying this unit was to serve as an emergency power back up supply..
Having worked for a small company that installs emergency backup power systems, a key lesson learned was to go with propane since it doesn't deteriorate in long storage and you never have engine/carburetor gum up problems as you do with gasoline power units.
A copy of NFPA 58 code and a local knowledgeable propane dealer was very helpful in laying this system out to ensure compliance with propane fire & DOT codes.
While I have done some welding for hire with this unit, it has been primarily a hobby welder and home emergency back up power source.