beardking, my first streetbike was a Nighthawk 650. I rode it for about 3 years before taking on a passenger. Fortunately for me, it was a classmate from college who, like your co-worker, was probably about 100lbs soaking wet. To make it interesting, I lived on a farm too - had to ride at least 4 miles of gravel before hitting pavement, but the direction I went usually required more like 8 miles of gravel. (however, growing up in that environment & driving it every day makes for sharp skills - it didn't bother me because I new how to handle it)
I think if your wife & your co-worker can work out a mutual respect for the situation, that might be a good idea to try... IMO.
Abba Zaba, you my only friend.