O.K. is preloading really an issue? I think ball bearings are not as good as the tapered bearings for this application, the tapered bearings handle the side loads better, and I think, and (could be wrong) but don't ball bearings have a much smaller contact patch than the roller bearings? I don't think I would use ball bearings. Consequently all of the landing gear components that I have collected in the last ten years, not a single one has a ball bearing in it anywhere, mostly just bushings. (with the obvius exception of the Berkut which I have replaced the ball bearings with bushings.
Tony