Thanks guys. Surly got back to me concurring with what FKMTB07said above.
I'm getting great traction from my Nokians (already over-speced on the Steamroller at 40mm) so no tire issues here. I'll take what wheelbase lengthening I can get by adding a chain link or two. Maybe then I'll at least be able to fit fenders.

I'll also go with rudetay's suggestion and replace the bull horns with a much wider Origin8 Gary bar I have.