The inverter to handle that load would cost twice what a premier power welder costs, not to mention it would be huge and a ppw can burn 1/2 steel with no trouble, try that with a 110 welder. If you want a onboard welder because it would be "nice" to have one along "in case" just carry (sealed well) some welding rod of different sizes and grades.
Two batteries and a couple sets of jumper cables, this will get you out of most pickles.

If you see yourself trail welding a lot...get a PPW.

SD