The unimproved roads in the park mostly require a high clearance vehicle. I have covered most of them in a Dodge van and a Suzuki Sidekick. It would be unusual to find one that the Cherokee couldn't handle. Not all sites at the Rio Grande Village store can handle the 45 footer but he can always default to the Rio Grande Village Campground where he can park in the generator zone. I don't care for the campgrounds outside the park. I agree with doing Hwy 90 and somewhat with Hwy 170. Try to catch an evening ranger program while you're there.