The best photo I have is probably these of Chris Mann in the Restaged US Tour:

You can see more - and an explanation - in this photoset. And yes, it is a more recent addition to POTO in terms of the Phantom wearing it. It reminds of 'Love Never Dies', where the Phantom does a similar disguise stunt as a bartender. But original POTO features actual stagehands and actors wearing these type of costumes throughout to the show. Kinda feels like they sat there with all these costumes and decided "Hey! Let's have fun with them!"...

Here's some of the stagehand costumes used in the original staging - but then worn by people who either do stagehand work for real, or within the play (and not being the Phantom). The most prominent viewing is inside the elephant in Hannibal:

And carrying dead Piangi across stage:

I guess members of the mob chasing into the Phantom's lair in the end of the second act could also qualify as stagehands:

It varies what kind of headwear they use, if the waistcoat is single or double breasted, if they wear a necktie, and if they wear an apron - there is a large variety. In the original design Maria Bjørnson added rare workwear quirks like a printmaker's hat (literally a hat of folded paper, looking like a box), separate knitted or sewn sleeves, and a wide array of aprons and tool belts. Her level to attention and a dash of historical accuracy will never fail to amaze me! But a typical stagehand costume in POTO may look like what Dustin Layton wore in Las Vegas:

Which, with variations and a different hat, is what they have the Phantom in disguise wear in the Restaged Tour.

scanned a page from my sketchbook of a design I had banging around in my head for a while. I've seen these figures off and on in my dreams, and I've started calling them 'the hounds'. They're like stagehands, except reality is the stage. If you look closely enough, you'll see them rearranging the world around you: they replace the leaves to show the seasons changing, they roll in curtains to have the night fall, that car is replaced by a wreck, that person flying through the air is held up by them... I imagine that people who can do magic simply know how to instruct these hounds better than anyone else.