Cupcakes' Surly Cross Check

Have you thought about going for the Planet X Kaffenback instead? same geometry but with disc and derailleur.

Kaffenback would probably be the ideal way to go but a new one would mean,

• buying a new (relatively expensive) wheelset
  
• using clamp on mounts for the lowrider which I'm already not too sure about, they are the main thing putting me off the Muddyfox idea above
  
• still possibly having issues with the rack fitting around the around the disc caliper
  
  
  

I've been looking for older canti mount ones on ebay.