Even if you know it will be "wrong", go with the box art mate, otherwise people will notice and point it out. At Farnborough I had at least two people point out (very nicely and politely) that I had positioned one of the cars on my SR-N4 hovercraft diorama in the wrong place - they weren't wrong either, and I had a picture of the original box art attached to the diorama, so it was there for all to see!
Cheers
Al.
P.S. If it bugs you, you can always repaint it to the correct colour when you get it back after the Telford display (and UK tour next year of course
).
P.P.S. Found a photo to illustrate the point - notice how in the box art picture the green car has only just left the ramp, whereas I've positioned it a bit further away - two people picked me up on that alone (but ignored the missing van to the left - which doesn't come with the kit anyway!).