I've had costume pieces to help with sightline issues -- a hat, gloves, etc.
Some companies have a protocol of all personnel on deck (carps, props, ASMs, etc) wearing Dickies jumpsuits. When I worked in this context, there was a great big rack of jumpsuits, and on the first day of dress rehearsals all the deck folks would grab the one that fit best, slap a label in it, and they would be laundered weekly or as needed. It was great -- backstage tended to be chilly, and the jumpsuits had ample pockets and belt loops for tools and other small items.
My biggest worry when costumed deck personnel came up was always safe, comfortable footwear. I can do nearly anything in a dress, or pants, or whatever getup... but I take my shoes very seriously.