Wyeast 3068 Under Pitching and Contamination

[GranolaEater]

I am about to make a standard hefeweizen (60:40 wheat to barley) and i want to under pitch (50 billion cells in a 5 gallon batch) to enhance ester production. Also I plan to open ferment at 60F but I am concerned about contamination. If I use a diffusion stone to add pure oxygen for a min and a half would it allow for a vigorous enough fermentation keep the beer healthy?

 

[COLObrewer]

As long as fermentation starts off you don't have to worry about contamination. However, if I were worried about contamination, I wouldn't open ferment, what is your reason for the open ferment?