More on chain stays; My classic Miyata 1000 has 16" (41cm) stays, the Cannondale tourer has 17.5" (44.5cm) stays, and my Bruce Gordon BLT has 18" (46cm) stays. My size 13 heels still hit the Nashbar bags on the BLT with the 18" stays. The BLT would be the best ride for the OPs' trip but not on his budget. On such a long trip you have a lot at stake. Buy your bike at home and do short tours over there to get the problems worked out. Do not risk a year of your life on an untried system.