According to NHRA rules, any wheel spacers used must be located concentric, either by the alxe hub, or the bolt/studs. I don't see how it's possible to locate them on the hubs with a floater hub, sense there is no hub, only a flat surface.
I for one cannot understand why spacers would be allowed on a car with that much HP, and i'll bet those rules will be changed in the very near future, if in fact that was the reason the wheels came off.
JMO
Zip.