I would look at a BF tandem for max demountability.
I don't know if it would be a good idea in general, but if I was doing it I would go with the old demountable sytem where they put the shifter under the (rear) seat. The person in the rear position could shift and operate a rear brake, and the front would have a pair of front brakes. If rigged that way it is much easier to break the bike up without worrying about cables, and I like that kind of thing. Might not be worth it for most. And it makes it tough to ride the bike as a single, but the beauty there is the BFs can be configured as a single as well, so that concern is lessened.
Here is a fuller size demountable by Arvon Stacey. He handles the rear segments so they can be configured with the front segment as a single.