Was He a mere mortal man with fear and trembling acting only "in persona Christi" and not as our Lord, re-presenting to the Father in an unbloody way His once and for all time sacrifice?

If not, why would you raise these questions?  
The idea that either form of the Roman Rite should be a play-acting of the Last Supper is not to be found in Sacrosanctum Concilium nor anywhere else in the teachings that emerged from Vatican II nor, for that matter, in the tradition of the Church.