I got the seat cushion from Costco.  $19.  the lumbar support off of Amazon.  just replaced the lumbar thing, because they dont do all that well in direct sunlight. a few straps got brittle and fell apart.  it still lasted almost 3 years.  it comes in a two pack for $25ish, so I had a spare.  I think they were made for an office chair, maybe a car? I had to cut the strap that goes around back and knot it behind the seat back, to clear some braces and cords.   then two zip ties holds it in position up top.

 

it makes a huge difference.  I noticed my back was getting tired when I realized the old one had failed.  I am good to go.

 

just wanted to put this out there in case some of you have a fishing kayak marathon coming up.

 

? 

I'm looking for ways to do this as well. After about an hour on the water my feet start to go to sleep. I just feel that would be better if I could raise the seat a tad. My kayak has a higher seat setting too, but it doesn't feel natural at all. The one time I tried it in the high setting, I paddled right back to the dock and lowered it.

Not exactly the same thing, mine being a canoe, but I use a seat cushion, one of the Purple ones, you can get different thicknesses.

Good job..

side note.  if my seat ever fell in the water, I think the seat cushion will float it.  it is attached by a strap in the back.  those Hobie seats are costly!!   the salesman admonished me repeatedly telling me to NEVER forget to clip the seat in.  

My pedal drive floats supposedly. Hard to believe. I've never tested it.