Very few I'd have thought as it sounds like a bucketload of work for small reward - on the real thing the band is barely an inch wide.
I'd be interested in knowing your source for saying it's black. I have a copy of drawing 101837 dated July 1934 which states that droplights & the edges of their openings are to be painted 'Mahogany' colour, but nothing that pre-dates this.
AFAIK this practice continued until the end of the GW.
Pete S.,
C&W Dept.,
GWS Didcot.