I also built a Spindrift from B&B, and we love it! Ours is the 11' model, which nests to just under 6', They have a 10 foot model that would be closer to what you need, but you would still need to be creative to get down to the length you need.
We have two kids, so capacity was a big issue for us. We also used some ideas from other builders to make the bottom of the dingy "clip" together, and only have bolts on the top. This means the two halves will float independently, so we can put it together (and take it apart) in the water rather then on deck which I think makes a huge difference.
Good luck, I'll look forward to hearing what you come up with.
1964 Islander 32
Saint Helens, OR