wow, found my old post. I ended up going with a Shevron dash mat. It fits pretty well but would not recommend getting the black one that I did. It's made of a very reflective material that puts a lot of glare on the windscreen - the exact thing I was trying to get rid of. I think it is still slightly better than no mat at all though...
https://www.fitmycar.com/au/nissan-skyline-sedan-v36-2006-2014-dash-mat-shevron/5041?gclid=CjwKCAiAwJTjBRBhEiwA56V7q_LLgiv62fRtcL-3echLL59V1e-MxV_XyHSxllMGcOsEF-SFkvvknRoCCk4QAvD_BwE