Thanks everyone
I wound up all but eliminating the bearing entirely. Instead, I designed my own which ought to be as equally effective as something commercially available, and it's probably lighter (though not cheaper, I'm sure.)
The entire thing needs to be manufactured from raw materials, and I probably just reinvented the wheel, but it meets all of the criteria I wanted from it.
We'll see if we decide to use it in just a few weeks. In either case, I'll be more willing to discuss it later on in the season. It's nothing I've seen done before in my reasonably limited experience.