I decided to go with the gobs of epoxy route of sealing the hub to my printed parts.  

I also smoothed out the mating surfaces with extra epoxy, filed it back down, and then re-drilled all the holes to ensure that my screws don't crack the relatively thin printed rim.

I printed a slightly thicker o-ring, sanded it, and wrapped it around the circumference in Teflon tape.

This keeps the tape in the proper orientation to seal around the ring and in the grooves. The tape is strong in the long direction, but weak across the tape.  Across the width the tape can deform to fill voids.