<< The problem is the nature of the weld rod and burning through the
thin deck. >>
One has to burn through the deck to make the specified 5/8" puddle weld. A
special rod is manufactured specifically for this operation although a
medium (5/32") sized 6010 will do in a pinch. The special purpose welding
rod is extremely fast freezing. I don't know if the rod even has a AWS
"spec" designation. The trick is to have the weld amperage turned up higher
than normal and "choke" the arc closely.
Been there and done that by the acres.