I missed your interlocking corners; although I like the holes in the pad for the vertical rebar the best ( and the masic internal coating). Looks Good !
Overengineering might be stainless rebar so you could switch to salt water at some time.
Nothing personal , but as an engineer, I have never been impressed by the mechanical abilities of architects. One super architect screw-up I was familiar with was the replacement of the marble skin of the Standard Oil Bldg in Chicago . It cost more than the original building.
I wouldn't mention using A36 steel as it is the lowest common denominator for structural and plate; It would be difficult to find a piece of mild steel that did not meet the requirements of A36.