New layout Change of plan,

Well, I've finally given up on 009, it was just to difficult to get it to run properly, So ive changed to 00 ,,,
I managed to bid for, and get a job lot of track enough for stage one of my layout, which is a loop with two bays theres enough track to do that and hopefully a couple of sidings, i'm reusing the old boards from the 009 layout,

I also managed to get an 4F 0-6-0 Loco, a job lot of Ratio coaches 20 in all, some unbuilt, some started, and downloaded an station building and platform, that i printed onto card, and built up, i made the station with a long platform, and two shorter bays,
My plan is to have either an S&D theme, or Country branch line based on joint Midland / Southern stock.

I intend to sell on some of the coaches, as i don't need 20 coaches, keeping possibly 10, a rake of clerestory and rake of midland low roof, I only paid £31.00 for them, so i should if i can sell them, get my money back,
I'm watching the bidding on an 2P 4-4-0 hopefully if it stays cheap enough, that will go nicely with a rake of 5 clerestory coaches,

Now, here's a question, i intend to try to fully line out the panelled coaches using a very fine gold paint marker,(.004) Has anyone got experience of doing this, will it be fine enough, to line inside the moulded sides of the coaches,