If you think that you might have trouble holding the bike upright when stopped and pulling then you might be better off with a 2 wheel trailer such as a Burley Nomad.
As I said I ride with a small bag on a rack up front to balance the bike front to rear. I have used the BOB as well as panniers and right now feel more comfortable with panniers on the bike. I can still carry 40-50 lbs. of gear and I don't think that I want to try and pull any more than that up a hill.
When on tour the SS is more about relaxed riding. Lean back, relax, pedal and enjoy the sights. The miles will drift by and you will see a lot and not be near as tired at the end of your day and might find that you did about the same miles as if you pedaled hard and got tired out faster.