Phil is good , they now offer an accessory mud shield. additionally,
when sliding an O ring on the spindle
or a few if using a long spindle, before re attaching the crank arm adds another seal,

I did this with a Campag *Triple, O ring squeaks a bit when the weather is dry, because its there
and the O ring seal is touching both arm and the outside of the BB.

* ISO square taper.