your wife's involved? now THAT's special...wavygravy is also thinking of doing a tandem as his wife has always been a passenger, that's their style. be neat to see this trend take on steam.
one time, 2 riders (i won't say who. don't try this at home ) wanted to see how well a 70 would pull a tandem...so one held onto the other's elbow & off they went. 2 riders & 2 bikes, one engine...20mph easy.
I'm building my first, with probably another to follow for a friend of the customers. Using a 33cc Rackmount, but what I wanted to tell you was the fella priced 4 places, including some Target special, chose the Sun Drifter 7 speed from my dealer.
Sun has three choices on the website, he/I chose the 7 speed because of the lower walkthrough on the backseat.
My dealer priced it, with all my tire/wheel reinforcements and 12" gel seats, at $550-575. I don't know what kind of discount I'm getting, but the price with my adaptations were $100 less than anything my customer found.