Amyp,
Back to the bike... Have you researched if you can mount racks? I only looked at your bike on the Terry site and it looked like putting racks on may be a challenge. I know Arkel sells a light touring rack that attaches to the seat post and nitto makes a front rack that uses clamps to attach to the fork. Personally I don't like a front handlebar bag that attaches to the handlebars as it affects how the bike handles so I use a front rack that the weight of the bag rests on. Perhaps taking the bike to the LBS that carry's touring gear is in order. Best of luck. The trip sounds like a great time and as there will be tons of towns you won't need to carry much in the food department so the Arkel or a Revelate bag would fit the bill. (look at the Pika)