A lot of variables come into play here. How far is your planned tour? How many days would you like to complete it in? Do you have extra days if you need a rest? Are you self suporting or credit carding? Are you going with a group that is in much better shape than you are?
Answering these questions should make it clear what you need to do. Make sure you make a least one FULLY LOADED practice ride. Riding with even an extra 20lbs on the bike makes a difference.