Something that fits well should be a priority, as others have suggested.
I also agree that folding/disassembling tandems could be useful for your application, but as a former owner of a Bike Friday tandem, I'd suggest going through the disassembly process before you buy. I only took mine apart maybe twice, and it was always a bigger project than I expected. Mine was a late 1990s model, and it's possible newer models have better designs that are faster to disassemble.