First off let me say I "can" gap weld steel. I prefer a good fit-up, proper bevels, and most importantly, nobody inspecting my work, but...
I've got a situation where I cut a part in two with a grinder and a zip disc to only use part of it, and now I've decided that was a mistake. Or rather the application has evolved to a point where the original part would be better. I don't have to make it exactly like it was, but kinda sorta close maybe might be nice.
If it was aluminum and I was in a similar situation I'd grab one of the piece of stainless bar stock I keep for aluminum backing and just do it. I'd probably clamp it up, weld it up from one side, back grind it with a burr, and weld the other side.
This is steel. While its not any kind of acceptable practice if I tried the solution above it would weld right into the stainless steel backer. Is there any shade tree backing I could use beside buying an expensive piece of graphite?
I know. I know. The true correct shade tree engineering method is to just gap weld it. LOL.