Not my favorite, but as as last resort, you can always do a little tire stretch. This will make sidewall to incline inwards, thous creating the extra space to clear tire and wheel well...also this would kind of hide the poke, as the tire itself will be less wide.
20mm spacers was not a very good idea.
Oh, yeah, for the extra cost you can probably shave off 5-10mm of that spacer, but this depends on the depth of the newly drilled holes.
2004 BMW 325i, sedan, 5spd.