It's doable.
Prior to my trip to Vancouver this summer, I just biked every day to school and around town.
Day 1 to Canmore was about 80km (I thought that was a lot).
By day 8 or 9, the longest I cleared was 220km in one day, and that's over the Coquihalla in the Rockies to Chilliwack.
Average went from 100km to 160km per day overall.
You build up endurance over the trip. Nothing in the gym can really prepare you for it. Nothing like 50km of wind going against you while trying to climb a 7% gradient uphill with total weight of 220kg.