Steep climbs with a number of momentum-killing turns, so you'll need to lay on the power, which will get scarce the higher you go. Even at park entry in summer you'll be 15% down on power, and closer to 35% down across the top. Make sure your cooling system is up to snuff -- warm, thin air coupling with having to work the engine will definitely be a touch of stress on the cooling system (but nothing it can't handle, as long as your radiator isn't full of bugs and dirt and your coolant levels aren't low).
The Green Machine -- 2000 Mountain High Coachworks Summit (Spartan chassis / Cummins ISC)
...and F-Troop: Fearghus, Fiona, and Frankie (Cairn Terriers)