Chris, you're missing the point entirely.
It was Rick Grimes playing the engineer. His penis is so huge that it would've meant zooming out to get the whole thing in, or a whole shit ton of prosthetics to reign the puppy in.
As is, a loincloth with a tie-back is the cheapest option. That or sling it over the shoulder, but Rick only does that on weekends, and they shot that scene on a Monday.