Unearthing this thread, because I am still looking for an example of a rear rack known to fit and work on a Calfee tandem. I know that this or that brand or model should work, but I'd be a lot more confident ordering the make and model that actually has worked. I've done some image searching, and tandems with racks are easy to find, and Calfee tandems are easy to find, but I can't find a Calfee tandem with a rack.
Mrs. R is down for a one-night credit card tour foray, so to dip the toe in touring, and I've got to find a rack to carry her panniers.