I'm also printing MkV(B)! Helmet looks great, keep it up. My experience has been one of patience since there's just SO MUCH to print, but I've been focusing on learning about my printer and really making the quality as high as possible.
For visors I was actually planning on doing a vacuum formed one, I'm really interested to see how a motorcycle visor will work though it could be a great option if the trimming gets it to sit flush!