I notice you have no thwarts. When studied, a thwart's primary function is to resist the sides pulling further apart in case of a folding disaster. F'rinstance, if the boat is bridged - both ends are well supported, and the center is bridged up with no support - any weight in the center (like, say, a fisherman trying to regain ewuilibrium, but stumbles) the ends of the boat can fold upwards, bending the middle of the hull open. An extreme example, the boat would fold completely double, and the ends would be nearly touching. While that isn't ever likely to happen, hull damage would probably occur in the first 5-10 degrees of bend.
A thwart resists the sides flexing outwards, and therefore resists hull deformation beyond the point where you hear loud cracks and pops.
All that being said, canoes and pirogues usually have thwarts made if wood. Wood will resist stress of both compression (sides squeezing closer together) and tension (sides are stretching further apart). Situations where the sides might squeeze closer together are both highly improbable, and fairly difficult to do. Therefore, an effective thwart need only withstand tension. Therefore wood is unnecessary as a thwart. ROPE, on the other hand, is a perfect thwart. Inexpensive, lightweight, and easily installed - especially onto ventilated gunnels. I thread through three blocks on each side of the boat, and do a trucker's hitch across the center. This serves nicely.
Frankly, you can tie it into place quicker than reading this entire post. Sorry 'bout that.