Joel, I also run into this a lot. Mostly with black insides of car interiors or bikes. My preference is to paint the outside first, then hand-paint
![Shock [:O]](/FSM/CS/emoticons/icon_smile_shock.gif)
the interior. It's not as (a) difficult or (b) bad as it seems, since you'll see very little of it - if you're sceptical about brushwork.
Since you have the darker colour on the outside, it makes for a bit more interesting challenge. In this case, I'd tend to paint the silver first. Then mask some of the vents (and other aero slits) from the inside and "merrily blast away" with the red. That should do it, but if not, it will be an easy fix to get rid of some red powder that might have creeped through. Also (this is just the way I do it) I tend to build up as much of the shell as possible before doing any painting. No worries about glue spills/runs, having to re-sand some parts, etc...
I also just had a look at my 206 - it is what you're doing, isn't it...? You see VERY little of the inside of the body shell, even if you turn it to all funny angles. Basically wheel-arches, etc.
Did you get sorted on those decals? It's a stunning colourscheme - when was it used? I had a look and could find no such decals, sorry. If you know where it was used, we should maybe have a look at the 206 colour - was it not maybe yellow on the car you have a pic from only and white on others? (If not, I can't believe such an error... where did you get the kit/decals?) Or was it only the one car that ran with this scheme - and only for one race?