I did my first tours in 1980 on a Schwinn Super Le Tour. I had a Blackburn Rack and Cannondale Panniers. I had and still have size 12 feet and didn't have problems with heel strike. I would suggest that you evaluate your tour and decide if the gearing will be sufficient. If you are riding across Illinois, which is pancake flat, the gearing will be fine. My wheels had alloy rims, if yours are steel then that is one place that I would upgrade, just to improve braking. Most other upgrades should not be necessary unless you want to change the gearing. That is all I would do for the first couple of tours and when you catch the touring bug start looking for a better suited bike.