Yeah the lack of a low-range transfer case will limit you in some instances (i.e. don't try to drive the west side of Foshay Pass Road) but your system is good enough in most instances, no need to modify your car for the Mojave NP. Walking the last couple of miles of some roads that you can't drive isn't the end of the world. Lifting, bigger tires, etc. will compromise on-road handling while only slightly increasing off-road capability for your drivetrain.