Tough question. We're kinda thin on experience with custom install jobs like that here. It's more slanted towards off-roading and the common buyer's needs.
My advice is go to an installer and ask. Pay attention to him and if you get a funky vibe, walk away. You're talking about an expensive install so be sure, for sure!
All these LCD installs are making me jealous!! I want a Navi now!! but not Toyota's. It pisses me off when they integrate the radio with the Nav making impossible to replace the radio with something worth listening to. :50cal: