That's odd. A 58mm diameter filter should be no wider in diameter than the end of the lens with the 58mm diameter threads. After all, the EW-63II filter has a 63mm diameter opening, and that really should fit over a 58mm diameter filter with room to spare!


I have never had an issue with installing a lens hood over a filter with a diameter matched to the lens (and in some cases, wider - the hood for the 85L, which has a 72mm filter thread, actually installs over a 77mm filter mounted with a step-up ring).


I should ask, are you sure you have the 58mm B+W XS-Pro filter? B+W makes several styles of filter mounts. There are three styles that are the same diameter as the filter threads - the F-Pro is their standard mount, XS-Pro is a thin mount with front threads, Slim is a thin mount (slightly thinner than XS-Pro) without front threads. But there's also an 'extra wide' mount (sometimes called 'oversized') where the filter glass has a larger diameter than the threads - it's essentially a combination of a step-up ring and a larger filter. If sounds like you may have the 58mm extra-wide filter. If so, you don't need that for a 28mm lens, even on a FF body - I suspect even the F-Pro mount would not vignette on a 28mm f/1.8.


Edit: Forgot to answer one question - given the choice, I'd take a hood over a UV filter. The former improves the quality of your images (by reducing flare, increasing contrast) protects the front element, while the latter only protects the front element.