To be honest, if you want to fit a double din unit you will have to do some cutting, all double din units are more or less the same on the back, only BMW for obvious reason make a large screen unit that will fit in the hole.
Alpine do a vehicle hub system which just has a monitor up front that you could fit, all the brains go in the back or somewhere else you can fit them, but from what an acquaintance of mine who had the system was telling me it really isnt worth the hassle, which is annoying as Alpine are one of the best car audio manufacturers.