Thanks for the replies. It seems this is sort of thing's not been done before then.
Bernard - I'm always lurking around here. As soon as I read loren's reply I thought about adding humps to the dash part. Of course, the dash is a separate part! I've been in and out that GP4 file often enough - I should have thought about it and feel embarrassed now!! I'll give it try (adding the humps to the dash) and see how it goes.
I have to use a custom dash anyway because of playing across three monitors. To get a really cool view I have to have my cockpit view zoomed in quite a bit as you can see on the screenie. As a result, I couldn't see the pit-in warning lights, or the plank wear lights etc etc. So I've had to move them up on the dash. If I go for a wider field of view the cockpit looks to long and narrow and it feels weird.
That's one of problems with triple screen. I also have to make custom visors, again to suit the three monitors. Since I had to paint visors and cockpits, I painted all the pitstands and garages etc to 2010 too, so that's done at least. You can see some of that in the screenie too. Now, there's just this cockpit hump thing left to sort out now.
@kewell_fever: I'm using TripleHead2Go, not eyefinity. I imagine GP4 will go fine in eyefinity though. Apart from the wider visors and higher dash parts mentioned above, I've also had to alter the font file used for the main GP4 menus to suit triple screen. Other than that everything else is normal.