Hi ThomThom (and of course the other too...!)
I'm using really often Vray renders + Skechup lines, and I came up with an other solution than yours to solve the distortion problem, maybe it can help to share it.
In fact, to be honest, the 'out of the box' Vray Presets (for sketchup) are really bad and does not shows the true potential of this software...
Everything is linked with this physical camera, and if you want to kill the distortion, you have to switch it off.( the only basic effect that you loose is the vignetting, that you can had easily add on Photoshop... and it's a bit the same for the other ones, like exposure, etc...).
The only problem then , is the fact that everything gets burnt by the sun light, which normal level of intensity is set up to match with physical camera's sensibility.
So, the solution is to reduce it, to match with the normal camera sensibility. After many test and a lot of strange results, it appear that an intensity of 0,00005 (don't ask...) is just fine, and give the same result than 1 with the physical cam. Then, everything works perfectly, and you can render directly matching pictures and 2 point perspective or 2D views!
You can find this settings in the presets on my website, and I've just done a quick translation to make the non-french speakers able to use them. Their organisation is quite logical, so I think you will find out how they works...
I've also modified the original lamps to match this settings, and to make them more easy to use. (just drag an drop the lamps into your component folder, and when you use them, explode before, if you re using a Vray 1.0, because it bugs when they are into a component... watch this page to find out more http://www.wip-archi.com/wip-visualiser/vray/le%C3%A7on-2-lumiere/
Let me know how it works in your models, so I may improve the presets...