I have about the second largest generally available SUV (just slightly below the Ford Excursion). 300+ HP V8, 4x4 version. No special mods other than the highest rated tow hitch I can use. A winch would be nice, but not really to practical without some significant mods up front. Its large enough that we could pack it full of enough provisions to probably get us through a week or so, longer if we could find a good source of water. Big enough where we could shelter inside it necessary.
I do live in an area where there a legit natural disaster concerns...we have a tsunami warning system, forrest fires are a real possibility, as are earth quakes, and mountain issues. I'm pretty sure that as far as getting what I have someplace, my vehicle about as capable as I can afford all things considered. Meaning, I don't have the coin to trick out some old military heavy duty personnel carrier to something like that.
But the V8 & 4x4, short of really stump jumping or deep river crossing, if its a passable road, field, etc., it should get the job done.
BOSS