I'm suddenly thinking The Oregon Trail - with zombies! On one hand, modern materials/medical knowledge (nylon coats, plastic and aluminum cookware etc) would reduce the hardships of the trail well below the historical mortality rates. Of course, the reanimated threat was probably less of a problem in the 1840s. (Or was it - for those of us with Fistful of Zombies...)

The one catch with the horseclan sort of approach is animal care. Machine maintenance can generally be taught from a book, they fail in predictable ways, and usually stay where you put them. Animals have their own frailties and to varying extent personalties - modern people would probably have quite a bit of difficulty adapting to such.

Twilight 2000 had some very in depth rules covering this sort of thing. Rules for how much methanol fuel could be produced in an 8 hour period, fuel consumption for tanks, the yield of fishing with grenades... An increasingly archaic setting, and character creation required a spreadsheet - but you have to admire GDW's attention to detail. It also stands out as one of the few games to have a specific skill for handling nuclear weapons.

Getting back on track - what kind of climate would we be searching for? A place with strong winters would have the assorted hardships of the cold, but snow is a viable water source, and if zombies freeze - then the threat is lessoned for a few months. A warmer spot would have less fighting against the weather. Tropical is probably a bad idea, given the types of pathogens and parasites - but depending on if zeds rot, a highly biotic place could have its advantages.
There is a fine line between hobby and obsession. I seem to have lost sight of it some time ago.