I plan for 100K's per day on tours by myself. My GF can't ride that distance on her own bike yet so I'd likely shoot for 50K with her or more likely we'd ride the tandem and shoot for 100K. Asking your wife to ride 160kms+ a day off the bat is a sure way to ensure she never wants to tour with you again and despite your planning you may well find yourself deep in the middle of hostile territory when she gives up and throws her bike into the bushes.

My advice is to err on the side of days that are too short for the first few tours. If this tour doesn't work with short days due to the spacing of services maybe this isn't the route to take her on?