A splice with self tapping screws is what ironridge requires. It's hard to beat the simplicity of that. Welding is feasible but you would want to bevel the ends, ensure complete joint penetration so the weld doesn't become the failure point, and then do something like cold galv like suggested above.
It is possible that your AHJ will want compliance to a code such as AWS D1.1 (structural steel welding code).
If that is the case, you will need qualified procedures for the welding, you will need to be qualified as a welder to that procedure, you will need a Certified Welding Inspector to inspect the welds, etc.
I doubt it will get to that point, but if they want a properly engineered system, it could happen.
I used ground screws and 2" steel pipe to support ironridge racking. It made permitting a breeze. They do all the designing/engineering and spit out the build requirements.
If you do decide to weld it yourself, use ER70S-2 wire. It has lower silica content and is less problematic when welding galvanized (porosity).