When I welded that leaf spring together, there was no internet to ask you with. It's been a little while.
Prolly true about DOT. You aren't even supposed to weld on a truck frame, despite the fact that zillions of street legal trucks have had the frame stretched, shortened, or repaired.
That being said, for the weld to be done properly, it was practically undetectable. Excess weldment is as bad as pits when it comes to high strength weld. It was all ground down pretty smooth. A little paint, and it was invisible.
Two years later...maybe not! The weld was stainless, so it would not rust up equally. I'd like to see Mr. DOT declare why one little band wasn't rusting though!