Talking about two tandems and a kyak. I did a trip like that a long while back, except it was three people, 1 tandom and me in a kyak. It worked out pretty well that way because the bulk of the gear went in the tandem and there wasn't as much of the packing/ unpacking of the kyak at portages. I just left the little bit of stuff I had in the hatches in there on the portages, took a little to figure out the balance but not too bad after that. There was two newbies in the tandem and I easily outpaced them with the kyak. For the portages, I used a kyak yoke that spring creek makes. It was a little hassle to strap it on and off at every portage but since I could travel faster I usually just kicked it up a bit before each portage and had it ready to go and often over the portage before the tandem got there so I could carry their stuff over also.