I was having the same problem. I solved mine by carving a seat out of a 4" thick closed cell foam block. My seat now is 16" front to back and supports my legs better.

I also had the same problem.

The trick is to put extra padding underneath your upper thigh to provide you with greater support. Not just the seat, but the upper thigh is most important.

Two options on the extra padding. 1. Use a THICK piece of closed cell foam and shape it into a seat which is most comfortable for you. 2. CLC sells a "thigh pad"  is one piece, inflatible and supports both thighs.

Finally, when you get in your boat, take the extra time to be sure that you are in "straight." I used to be less conscious of whether I was in a stable, balanced and comfortable position. I now take the extra time to get seated "just right" and I haven't had problems in weeks.

Hope this helps.

Tim Clark

I am battling numbness in my feet and legs as well.  I am going to make a seat out of mini cell foam and see if it helps.  The other day I rolled some foam up and made a thigh brace that seemed to help a little.  If anyone else has any advice on how to battle numbness I am all ears.  I can usually paddle for about 20 minutes before the numbness and pain begin.  I rented a tandem kayak with my wife a couple of weeks ago and was able to paddle for a few hours with no pain or numbness.  That experience has given me hope.