Thanks everyone for the comments, and the reassurance that as long as I keep the Spidertrax properly torqued, I shouldn't run into any issues.
Much to my surprise, Quadratec responded that with their Hardrock wheels, and my tires (35x12.5x17), I should not have any issues with rubbing. I am honestly surprised by this, as I would have expected them to come out and say there would be rubbing issues and such, because of any potential liability issues of their claims not being correct. Is there really any truth to these working, without the need for a spacer? It's essentially 0.75" more backspacing than recommended, so that translates to quite a bit more when you get out to the tire, especially at full steering lock.