two up on weeStrom
Particularly because neither you nor your wife is very large, your weeStrom should be very comfortable and have sufficient performance for riding two up. It is a little crowded for me and my wife. Although I am only 150lb, she is a "full figured" woman. Even so, she has more room behind me on the wee than she did years ago on a Suzuki VX800.
Through this forum or one of the others, I bought a second hand Corbin modular system. So, she has her own carbon fiber look leather passenger seat when needed. When I ride alone, which is 95% of the time, I replace her seat with a "smuggler" trunkette.
As others have said, just be sure your suspension and tire pressure are adjusted for the added load (no... strike that... should not refer to your wife as a load ;^)