BLACK ON THE OUTSIDE...
Considering style has such a large role to play in any drama was a bit skewered as to what look to drop for You Me Bum Bum Train. 'Wear old clothes that dont care about'. Tricky. Care about all, young and old. Considering archive D&G suit from 2000 that was a life changer of sorts. Mid grey pinstripe, dead fitted, sort of early Seventies. It's a bit dead too now, really, but maybe would work. Have fallen out of, been hurled through, skidded down various things in it already. A simple grey or navy suit can be just the ticket for an oldish style merchant who's keeping it on the low-key simmer, see last Style Referee (click).
Alternatively the all black Milk Tray man/special forces/mime look might work in as a neutral backdrop to what goes off...all black, military boots, thats it.. er...yes.
Note. Above shot of Brando is by Ron Galella, also in shot, who wears a helmet as Marlon had punched him previously. Message of caution perhaps?