We used Yokohama A/T-S on factory rims (with a full sized spare, 12V tire pump, 2 cans of Fix-A-Flat, and a plywood square to put under the jack on gravel). Yet, no flats. We ran reduced the pressures on gravel (~28 psi) and drove conservatively (32-39 mph). With LT tires, which these aren't, I'd have been a bit more confident. It's a loooong way to the nearest service once you get very far north! All the roads were well graded so there was absolutely no need for skid plates. We only encountered one incline where the soil supporting the gravel had softened from heavy rains. Maybe a hundred yards or so of wondering if we'd spin through the gravel and into the mud--the only time we needed "symmetrical AWD." Overall, we were impressed at how well the road was maintained. The flip side to regular grading is that sharp rocks get randomly arranged across the surface (many sticking straight up), increasing chance of punctures. I'll think about more pictures.
Thanks for you service! -randle