Thanks for the feedback, I see what you mean with the cab depth, I will have a look to see if I can improve it.
As for loco width, the gauge profile in the UK is fairly small so I don't think width difference would look too bad, here is a UK class 47 on a 12 axle trailer, it's actually narrower than the trailer. This is 12 axles long, I went for 9 as it will I think suit Lego loco lengths better.