As far as the stop distance is concerned,config 3 needs on an average about 90 mtrs more then config FULL.
And as far as tail clearance,a heavier A/C will actually have a slightly lower nose att than a lighter one on approach.
So essentailly both the factors will not work in concert.
A minimum amount of experience is definitly required to get the optimum perfrmance out of any type of a/c.
However,once that comfort level is acheived,looking for excuses to fly "safely" at the expense of fuel economy/expeditous traffic flow is a sure indication that you are in aviation for the wrong reasons