I'm confused... why all the concern over welding a frame? Are they heat treated, made from some exotic steel that stress cracks if you use the wrong filler rod?
I TIG and Electron Beam welded aircraft engine parts for 5 years and TIG welded car parts for 5 years prior to that. If something is heat treated, you anneal it first and then weld it and then heat treat it again. If you're concerned about stress cracking you pre-heat the area before welding... if it's steel it can be welded.
I can see if you don't know a good weld from a bad weld where you could get into trouble. But if you can weld it with a wire welder it can't be that fussy.
