I think that'll still be too short. Get a couple extra boards and do a scarf joint to make them longer.
Have you ever kayaked before? A short kayak is not really fun for a beginner to paddle. They don't track as well as one even a few feet longer. If I was you I'd shoot for 10 feet minimum, but preferably 14.
Yes. Ive been kayaking before. And canoeing.
