Waterproof = resists water; Girl-proof = resists girls. Looks like your kayak is somewhat girl-proof

just kidding.
While I am not a girl, I do have problems with my legs falling asleep (mostly my left one) on long paddles. One thing that has alleviated it is one of those inflatable themarest-type seat cushions. I blow it up then sit on it and let as much air until it is comfortable. it compensates for the inappropriate curves of the seat, and the slight squishiness allows the buttocks a bit of movement and momentarily relieves pressure points.