We bought a slightly used Co-Motion Primera Co-Pilot last year on eBay, complete with front and rear racks and five Arkel panniers. The bike has been awesome! We've taken it touring in Portland and Tucson and also traveled to Austin representing Team Fatty at Livestrong. Touring with it has been great and the S&S couplers make it fairly easy to pack and fly.
I do have experience with Steve Bilenky and retrofits with S&S couplers. I recently sent him a Carl Strong ti single bike to retrofit, but unfortunately the top tube was only 1 inch in diameter (and smallest coupler is 1-1/4). S&S will tell you he is the best and most experienced of their many builders. Get a quote - but I think with patience you'll be able to find a second hand travel tandem for only a little more than the cost of the retrofit.