Mine are now closer to 56cms apart which reduces the overhang of the boards in the back by moving the entire setup closer to the front. This also means one binding is going to be inside the carrier and the other will be on the outside. Most passenger cars probably won't have rails that's longer than 75cm I reckon.
Yakima recommends anywhere from 30cm to 91cm. They even include this lifter kit which allows you to angle the carrier on one side to clear any larger bindings.
Perhaps the better buy would have been Thule 7501s and the Fatcat 6. It would have been double almost even triple the cost of the Snowcat though.
If I had access to a metal shop, it wouldn't be difficult to raise the Snowcat by an inch or two.