I also have problems with my legs going to sleep. About 15-20 minutes after I start off, they'll get all pins and needles, if I dont move them around, they go solid dead, and it is painful sometimes. If I alternately lift one knee at a time up through the cockpit opening, and wiggle my toes around for a few minutes, they come back to life.

I've found that when I paddle with my Teva's on, or any other shoe, legs go to sleep. If I paddle in neoprene booties or barefoot, I have much, much less problems. In fact I just got back from a 4-hour trip, and my legs did not go to sleep once today. Booties on, sandles behind seat! Neoprene is more comfortable, cause it pads my heels a bit.

I'm not sure if it's a nerve thing, or a circulation thing. I've heard a lot bandied about regarding compression of the sciatic nerve, and the usual remedy is to "extend" the edge of the seat with some type of pad, which you've said doesn't work for you. I think the point there is to make sure there is no pressure point on the backs of your thighs from the seat edge. In your padding experiments, did you make sure the pads came at least level with the seat edge?

Another thing I've heard is that people with desk jobs often suffer shortening of the hamstring muscles, which can contribute. So stretching exercises for a few minutes every day might help.

I can't believe you're comfortable in your F-150! I absolutely abhor riding in my boss's F-150! But that's a personal opinion, glad it works for you... the way you describe the Ford seat as "suspending your butt" brings to mind the other recommendation about kayak seating, which was to make the back of the seat about 1-1.5 inches lower than the front. People also recommend putting a rounded ridge towards the front, between the legs, sort of like a tractor seat. So your thighs fit in like, channels.

Ross Leidy (I think) liked his production Dagger seat so much that he took a mold off it and now makes his own fiberglass replicas for all his wood boats. Check out http://www.blueheronkayaks.com/kayak/index.html. That seat looks like it matches the descriptions I've read about seats that prevent numbness.

Like I say, biggest thing for me has been to go shoeless. Not sure what that has to do with it, but it works for me.

Hope this helps you solve the problem! I know it's a pain!