Way back when, I got one of those generic roof carrier. It comes with 4 suction pod feets. I inserted long steel rods to strengthen it, and use s/s pipe clamp to clamp it to the H2 roof bars. It's just wide enough to fit the spare.
1) It was plenty strong, and since the carrier is kindda sitting on the edges of the oem bars (clamped tightly), the weight of the tires is not on the suction-cup feet (which would potentially dimple the roof).
2) It was a biatch to put up or down (though I did do it by myself -- by opening a tall ladder next to the H2, and "rolling" the tire up the rungs onto the car roof).
3) After seeing trail photos, it just looked too goofy for me.
4) I took it down & bought a rear-tire carrier.
